GE SPM Series, SPM-PF, SPM Instruction Manual
g
t
GE Power Managemen
SPM
SYNCHRONOUS MOTOR PROTECTION
AND CONTROL
Instruction Manual
Software Revision: 210.000
Manual P/N: 1601-0072-A6
Copyright © 2001 GE Power Management
GE Power Management
215 Anderson Avenue, Markham, Ontario
Canada L6E 1B3
Tel: (905) 294-6222 Fax: (905) 294-8512
Internet: http://www.GEindustrial.com/pm
Manufactured under an
ISO9001 Registered system.
These instructions do not purpor t to cover all detai ls or varia tions in equipment nor provide fo r every p ossibl
e
e
e
t
contingency to be met in connection with installation, operation, or maintenance. Should further information b
desired or should pa rticula r pro blems arise whi ch are no t cove red su ffici ently for the p urchas er’s purpose, th
matter should be referred to the General Electric Company.
To the extent required the products des cribed herein meet applic able ANSI, IEE E, and NEMA s tandards; bu
no such assurance is given with respect to local codes and ordinances because they vary greatly.
TABLE OF CONTENTS
1. INTRODUCTION
2. INSTALLATION
1.1 OVERVIEW
1.1.1 GENERAL DESCRIPTION........................................................................1-1
1.1.2 FUNCTIONAL OVERVIEW........................................................................1-1
1.2 ORDERING
1.2.1 ORDER CODES........................................................................................1-3
1.2.2 ACCESSORIES.........................................................................................1-3
1.3 SPECIFICATIONS
1.3.1 SPM SPECIFICATIONS............................................................................ 1-4
2.1 OVERVIEW
2.1.1 DESCRIPTION..........................................................................................2-1
2.1.2 ELEMENTS OF A SYNCHRONOUS MOTOR CONTROLLER................. 2-1
2.2 MECHANICAL INSTALLATION
2.2.1 UNPACKING THE SPM.............................................................................2-2
2.2.2 REMOVING THE DRAWOUT RELAY....................................................... 2-2
2.2.3 INSERTING THE DRAWOUT RELAY....................................................... 2-2
2.2.4 MOUNTING THE SPM.............................................................................. 2-2
2.2.5 SPM MOUNTING ACCESSORIES............................................................2-2
2.3 ELECTRICAL INSTALLATION
2.3.1 DESCRIPTION..........................................................................................2-4
2.3.2 GROUNDING.............................................................................................2-6
2.3.3 FIELD AND EXCITER VOLTAGE INPUTS ...............................................2-6
2.3.4 RELAY OUTPUTS ..................................................................................... 2-6
2.3.5 CURRENT TRANSFORMER INPUT.................................... .....................2-6
2.3.6 POWER FACTOR OUTPUT......................................................................2-6
2.3.7 DC FIELD CURRENT INPUT....................................................................2-6
2.3.8 EXCITER VOLTAGE OUTPUT MONITOR................................................ 2-6
2.3.9 POWER FACTOR REGULATION OUTPUT ............................................. 2-7
2.3.10 CONTROL VOLTAGE.............. ..................... ..................... ....................... 2-7
2.3.11 EXTERNAL VOLTAGE PF REFERENCE............... ..................................2-7
2.3.12 RS485 COMMUNICATIONS PORT ..........................................................2-8
3. SYNCHRONOUS MOTOR
APPLICATIONS
3.1 OVERVIEW
3.1.1 GENERAL..................................................................................................3-1
3.2 COLLECTOR-RING MOTORS
3.2.1 STARTING AND SYNCHRONIZING......................................................... 3-5
3.2.2 RELUCTANCE TORQUE SYNCHRONIZING........................................... 3-6
3.2.3 STARTING PROTECTION...................................... ..................... .............3-7
3.2.4 REDUCED VOLTAGE STARTING............................................................3-8
3.2.5 POWER FACTOR (PULL-OUT) PROTECTION...................................... 3-10
3.2.6 POWER FACTOR OPERATION.............................................................3-11
3.2.7 CONTROLLER ACTION DURING PULL-OUT........................................3-12
a RESYNC MODE......................................... ..................... ........................3-12
b RIDE-THRU MODE .................................................................................3-12
3.2.8 EFFECT OF VOLTAGE DIPS ON MOTOR POWER FACTOR .............. 3-13
3.2.9 POWER FACTOR DETECTION & INDICATION – OVERHAULING LOAD 3-
15
3.2.10 POWER FACTOR REGULATION........................................................... 3-16
3.3 BRUSHLESS CONTROLLER
3.3.1 DESCRIPTION........................................................................................3-17
GE Power Management SPM Synchronous Motor Protection & Control
i
TABLE OF CONTENTS
3.3.2 BRUSHLESS MOTOR REVIEW..............................................................3-17
3.3.3 STARTING THE BRUSHLESS MOTOR............... ..................... .............3-18
3.3.4 STALL PROTECTION ............................................................................. 3-19
3.3.5 POWER FACTOR (PULL-OUT) PROTECTION...................................... 3-19
3.3.6 POWER FACTOR REGULATION...........................................................3-19
4. USER INTERFACE
5. SETPOINTS
4.1 SPMPC SOFTWARE
4.1.1 DESCRIPTION ..........................................................................................4-1
4.1.2 SPMPC INSTALLATION........ .................................................................... 4-2
4.1.3 CONFIGURATION.................................................................................. ... 4-3
4.1.4 CREATING A NEW SETPOINT FILE ........................................................ 4-4
4.1.5 EDITING A SETPOINT FILE .....................................................................4-5
4.1.6 LOADING SETPOINTS FROM A FILE.................. ..................... ...............4-6
4.1.7 UPGRADING SETPOINT FILES TO A NEW REVISION.......................... 4-7
4.1.8 PRINTING SETPOINTS & ACTUAL VALUES........................................... 4-8
4.1.9 TRENDING................................................................................................ 4-9
4.2 KEYPAD INTERFACE
4.2.1 DESCRIPTION ........................................................................................4-10
4.2.2 CHANGING SETPOINTS ........................................................................ 4-11
4.2.3 CHANGING CALIBRATION VALUES............ .........................................4-12
4.2.4 CHANGING CONFIGURATIONS............................................................4-13
4.2.5 VIEWING & CHANGING STATUS MODE PARAMETERS.....................4-14
4.2.6 ALTERNATE MENU OPERATION ..........................................................4-14
5.1 OVERVIEW
5.1.1 DESCRIPTION ..........................................................................................5-1
5.2 SETPOINTS MENU
5.2.1 POWER FACTOR TRIP............................................................................ 5-2
5.2.2 POWER FACTOR DELAY......................................................................... 5-2
5.2.3 POWER FACTOR SUPRESSION.............................................................5-2
5.2.4 POWER FACTOR MODE..........................................................................5-3
5.2.5 FIELD APPLICATION RELAY DELAY ............... .......................................5-3
5.2.6 FIELD CONTACTOR AUXILIARY RELAY DELAY.................................... 5-3
5.2.7 AC CT PRIMARY RATING........................................................................5-4
5.2.8 MOTOR FULL LOAD AMPS......................................................................5-4
5.2.9 MOTOR LOCKED ROTOR AMPS.............................................................5-4
5.2.10 SYNCHRONOUS SLIP.............. ................................................................5-5
5.2.11 STALL TIME .................. ..................... .......................................................5-5
5.2.12 RUN TIME..................................................................................................5-5
5.2.13 DIRECT CURRENT CT PRIMARY RATING .............................................5-6
5.2.14 FIELD OVERTEMPERATURE (HIGH FIELD OHMS) PROTECTION.......5-7
5.2.15 FIELD UNDERCURRENT ....................................... .................................. 5-8
5.2.16 FIELD UNDERCURRENT DELAY................................................ .............5-8
5.2.17 FIELD UNDERVOLTAGE .......................................................................... 5-8
5.2.18 FIELD UNDERVOLTAGE DELAY................ ........................................ ..... 5-9
5.2.19 INCOMPLETE SEQUENCE DELAY..........................................................5-9
5.3 OPTIONAL POWER FACTOR REGULATION SETPOINTS
5.3.1 DESCRIPTION ........................................................................................5-10
5.3.2 POWER FACTOR REGULATOR............................................................5-10
5.3.3 REGULATOR GAIN................................................................................. 5-10
5.3.4 STABILITY............................................................................................... 5-10
5.3.5 REGULATOR OUTPUT LIMIT.................................................................5-11
ii
SPM Synchronous Motor Protection & Control
GE Power Management
TABLE OF CONTENTS
5.3.6 FLOOR VOLTS........................................................................................ 5-11
5.4 CONFIGURATIONS MENU
5.4.1 MOTOR TYPE.......................................... ............................................... 5-12
5.4.2 LINE FREQUENCY .................................... .............................................5-12
5.4.3 POWER FACTOR REFERENCE............................................................ 5-12
5.4.4 RTU ADDRESS.................................... ............................................ ....... 5-12
5.4.5 BAUD RATE ................ ..................... ..................... ..................... ............. 5-12
5.4.6 PARITY........... ..................... .................................................................... 5-12
5.4.7 TURNAROUND ........................ ...............................................................5-13
5.4.8 STATUS MODE....................................................... ..................... ........... 5-13
5.4.9 PASSWORD......................................................................................... ...5-13
5.5 CALIBRATION MENU
5.5.1 FULL-SCALE EXCITER DC VOLTAGE ..................................................5-14
5.5.2 FULL-SCALE EXCITER DC AMPS .........................................................5-14
5.5.3 FULL-SCALE MOTOR AC AMPS............................................................5-14
6. ACTUAL VALUES
7. TESTING AND
TROUBLESHOOTING
6.1 DISPLAY SCROLLING
6.1.1 DESCRIPTION..........................................................................................6-1
6.2 STATUS
6.2.1 MOTOR RUNNING HOURS...................................................................... 6-2
6.2.2 INCOMPLETE SEQUENCE TRIP COUNTER .......................................... 6-2
6.2.3 FIELD LOSS TRIP COUNTER .................................................................. 6-2
6.2.4 PULL-OUT TRIP COUNTER..................................................................... 6-2
6.2.5 RESYNCRONIZATION ATTEMPTS TRIP COUNTER.............................. 6-2
6.2.6 MISSING EXTERNAL PF VOLTAGE REFERENCE COUNTER.............. 6-2
6.2.7 CHECK EXCITER TRIP COUNTER.......................................................... 6-3
6.2.8 POWER FACTOR TRIP COUNTER.......................................................... 6-3
6.2.9 SQUIRREL CAGE TRIP COUNTER......................................................... 6-3
6.2.10 FIELD OVERVOLTAGE TRIP COUNTER................................................. 6-3
7.1 START-UP PROCEDURE
7.1.1 INSPECTION.............................................................................................7-1
7.1.2 SPM TEST CHECKS...... ............. .............. .. ............. ............. .. .............. .... 7- 1
a STANDBY MODE ...................................................................................... 7-1
b TEST MODE..............................................................................................7-1
7.1.3 START-UP DESCRIPTION....................................................................... 7-2
7.2 DISPLAY AND MESSAGES
7.2.1 DISPLAY.................................................................................................... 7-3
7.2.2 SPM MESSAGES...................................................................................... 7-3
7.3 REGULATOR TUNE-UP
7.3.1 INSTRUCTIONS........................................................................................ 7-5
7.4 TROUBLESHOOTING
7.4.1 TROUBLESHOOTING GUIDE....................................................... ........... 7-6
7.5 PROGRAMMING
7.5.1 PROGRAMMING EXAMPLE..................................................................... 7-8
7.6 DOs AND DON’Ts
7.6.1 DOs.......................................................................................................... 7-12
7.6.2 DON'Ts.................................................................................................... 7-12
GE Power Management SPM Synchronous Motor Protection & Control
iii
TABLE OF CONTENTS
7.7 FREQUENTLY ASKED QUESTIONS
7.7.1 SPM FAQ.................................................................................................7-13
7.8 REVISION HISTORY
7.8.1 FIRMWARE .............................................................................................7-15
7.8.2 SUMMARY...............................................................................................7-16
8. ACCESSORIES
9. MODBUS
COMMUNICATIONS
10. FUNCTIONAL TESTS
8.1 VOLTAGE DIVIDER NETWORK
8.1.1 GE POWER MANAGEMENT VDN............................................................ 8-1
8.1.2 GE MEBANE VDN.....................................................................................8-2
8.2 FIELD CURRENT CALIBRATION MODULE
8.2.1 GE POWER MANAGEMENT MODULE....................................................8-3
8.3 DC CURRENT TRANSFORMER
8.3.1 DESCRIPTION ..........................................................................................8-5
9.1 IMPLEMENTATION
9.1.1 MODBUS PROTOCOL.............................................................................. 9-1
9.1.2 PERFORMANCE REQUIREMENTS......................................................... 9-1
9.1.3 SETPOINTS............................................................................................... 9-1
9.1.4 EXECUTE OPERATION COMMAND CODES (COIL NUMBERS) ...........9-1
9.2 MEMORY MAPPING
9.2.1 MODBUS MEMORY MAP ......................................................................... 9-2
9.2.2 FORMAT CODES......................................................................................9-7
10.1 INTRODUCTION
10.1.1 DESCRIPTION ........................................................................................10-1
10.2 COLLECTOR-RING MOTOR FIELD APPLICATION TEST
10.2.1 SETUP..................................................................................................... 10-2
10.2.2 RELAY PROGRAMMING........................................................................10-2
a CONFIGURATIONS ................................................................................ 10-2
b SETPOINTS............................................................................................. 10-2
10.2.3 TEST ........................................................................................................ 10-2
10.3 COLLECTOR-RING MOTOR POWER FACTOR TEST
10.3.1 SETUP..................................................................................................... 10-3
10.3.2 RELAY PROGRAMMING........................................................................10-3
a CONFIGURATIONS ................................................................................ 10-3
b SETPOINTS............................................................................................. 10-3
10.3.3 TEST ........................................................................................................ 10-3
10.4 COLLECTOR-RING MOTOR POWER FACTOR TRIP TEST
10.4.1 SETUP..................................................................................................... 10-4
10.4.2 RELAY PROGRAMMING........................................................................10-4
a CONFIGURATIONS ................................................................................ 10-4
b SETPOINTS............................................................................................. 10-4
10.4.3 TEST ........................................................................................................ 10-4
10.5 BRUSHLESS MOTOR FIELD APPLICATION TEST
10.5.1 SETUP..................................................................................................... 10-5
10.5.2 RELAY PROGRAMMING........................................................................10-5
a CONFIGURATIONS ................................................................................ 10-5
b SETPOINTS............................................................................................. 10-5
iv
SPM Synchronous Motor Protection & Control
GE Power Management
TABLE OF CONTENTS
10.5.3 TEST........................................................................................................ 10-5
10.6 BRUSHLESS MOTOR POWER FACTOR TEST
10.6.1 SETUP..................................................................................................... 10-6
10.6.2 RELAY PROGRAMMING........................................................................10-6
a CONFIGURATIONS ................................................................................ 10-6
b SETPOINTS............................................................................................. 10-6
10.6.3 TEST........................................................................................................ 10-6
10.7 BRUSHLESS MOTOR POWER FACTOR TRIP TEST
10.7.1 SETUP..................................................................................................... 10-7
10.7.2 RELAY PROGRAMMING........................................................................10-7
a CONFIGURATIONS ................................................................................ 10-7
b SETPOINTS............................................................................................. 10-7
10.7.3 TEST........................................................................................................ 10-7
10.8 AC CURRENT METERING AND PULL-OUT TEST
10.8.1 SETUP..................................................................................................... 10-8
10.8.2 RELAY PROGRAMMING........................................................................10-8
a CONFIGURATIONS ................................................................................ 10-8
b SETPOINTS............................................................................................. 10-8
10.8.3 TEST........................................................................................................ 10-8
10.9 EXCITER / FIELD VOLTAGE METERING TEST
10.9.1 SETUP..................................................................................................... 10-9
10.9.2 RELAY PROGRAMMING........................................................................10-9
a CONFIGURATIONS ................................................................................ 10-9
b SETPOINTS............................................................................................. 10-9
10.9.3 TEST........................................................................................................ 10-9
10.10 EXCITER / FIELD CURRENT METERING TEST
10.10.1 SETUP................................................................................................... 10-10
10.10.2 RELAY PROGRAMMING...................................................................... 10-10
a CONFIGURATIONS .............................................................................. 10-10
b SETPOINTS........................................................................................... 10-10
10.10.3 TEST...................................................................................................... 10-10
A. COMMISSIONING
B. FIGURES AND TABLES
C. WARRANTY
A.1 COMMISSIONING
A.1.1 COLLECTOR-RING SETTINGS..................................................... ...........A-1
A.1.2 BRUSHLESS SETTINGS..........................................................................A-2
B.1 FIGURES AND TABLES
B.1.1 LIST OF FIGURES................................. ..................... ..............................B-1
B.1.2 LIST OF TABLES.......................................................................................B-2
C.1 WARRANTY
C.1.1 WARRANTY..............................................................................................C-1
GE Power Management SPM Synchronous Motor Protection & Control
v
TABLE OF CONTENTS
vi
SPM Synchronous Motor Protection & Control
GE Power Management
1 INTRODUCTION 1.1 OVERVIEW
1 INTRODUCTION 1.1 OVERVIEW 1.1.1 GENERAL DESCRIPTION
The SPM controls starting, synchronizing, and protection of collector-ring and brushless type synchronous
motors.
The SPM control funct ion s for s tar tin g sy nc hronous motors include ac cu ra te se ns in g of mot or spe ed an d ro tor
angle, allowing the unit to apply excitation at optimum speed and angle. This per mits closer matching of the
motor to the load. Optim um application of excitation al so reduces power system dist urbance, which occurs
when the motor goes through a comple te slip cycle with the field energized. In addition, the SPM can take
advantage of the extended stall time of a r educe d volta ge star t. It also res ponds with the proper applica tio n of
excitation in the event that the motor synchronizes on reluctance torque.
The SPM provides the functions necessary to protect the motor durin g startup and in the event of async hronous operation. D uring startup and r estarting, the S PM prevents over heating of the c age winding. To protect
against asynchronous operation, the motor power factor is monitored. Two modes of pull-out protection can trip
the motor if resynchroniz ation does no t occur a fter a programm ed time del ay. Motor run time and the number
and type of trips are recorded.
The SPM has an optional power factor regulator containing five adjustable setpoints that can be changed while
the motor is running for convenient regulator tune-up.
A backlit LCD dis play and keys allow user conf igurable setting ranges to meet many applications. The unit
comes in a compact S1 drawout case.
The SPM can be ap plied as part of a co mplete synchronous motor co ntroller. This consists of four parts. A
main device switche s the motor on and off the power system. Multifunction digital relays (such as the GE
Power Management 46 9 Motor Manageme nt Relay) provide stator protec tion. DC field p rotection and c ontrol
are provided by the SPM. The field contactor and field discharge resistor completes the control assembly.
1
1.1.2 FUNCTIONAL OVERVIEW
The DC portion of the s ync hronous motor (rotor assembl y) is prote cted and c ontro lled u sing a d rawout micr oprocessor based mul tifunction re lay. The relay is adaptable to either col lector-ring or b rushless ty pe synchronous motors. Protection features inc l ude all of the followi ng :
• Cage winding and stall protection during start
• Lockout feature to protect a hot rotor after an incomplete start
• Incomplete sequence trip due to failed acceleration
• Automatic acceleration time adjustment for reduced voltage starting
• Power factor (pull-out) trip with auto resynchronizing feature
• Loss of DC field current trip
• Loss of DC field voltage trip
• Field winding overtemperature trip
After a successful sta rt, the relay automatically applies the DC field to the rotor at a prescribed slip an d slip
angle to minimize mec hanical stresses to the shaft as well as minimiz es possible electrical t ransients to the
power system. This is achieved by a dedicated output to close the DC field contactor. The relay is also capable
of reluctance torque synchronizing (collector-ring machines only).
A dedicated output is prov ide d in the relay to enab le th e loa din g of the motor followi ng the DC fiel d app li ca tio n
and unloading of the motor following a trip and/or loss of synchronization (pole slipping).
Control of an SCR type exc itation syste m by me ans of a n analog output to maintain po wer fact or (PF re gulation) is available as an option.
GE Power Management SPM Synchronous Motor Protection & Control 1-
1
1.1 OVERVIEW 1 INTRODUCTION
The man-machine in terface (MMI) cons ists of a backlit alpha numeric displa y and a keypad to ac commodate
relay programming as well as viewing actual motor parameters which comprise:
1
• AC stator current
• Power fa ctor
• DC field current
• DC field voltage
• DC field resistance
• Running time meter (RTM)
Statistical data includes number and type of trips.
The SPM performs a complete system check prior to starting the motor.
AC BUS
48
SPM
86
94
MOTOR
LOAD
CLUTCH
COUPLING
Stator
Protection
(469)
Calibrator
DC
CT
DC SUPPLY
I
AC
V
AC
I
DC
V
DC
ANSI DEVICE NUMBERS
Field overtemperature
26F
Undervoltage
27
Undercurrent or underpower
37
Incomplete sequence
48
Instantaneous overcurrent
50
Power factor
55
Field application
56
Lock out
86
Tripping
94
Reluctance torque sync. / resync.
95
Autoloading relay
96
55
50
37
27 26F 95
48
94
95
56
96
701767A9.CDR
1-
Figure 1–1: SINGLE LINE DIAGRAM
2
SPM Synchronous Motor Protection & Control GE Power Management
1 INTRODUCTION 1.2 ORDERING
1.2 ORDERING 1.2.1 ORDER CODES
The SPM has all features built into the standard relay and programmable by the user to fit the specific application. The only option in the order code is for Power Facto r Regulation. Som e of the standard featu res require
an optional external hard ware package that must be ordered in addition to the relay it self. These separate
packages are explained in the foll owi ng se cti on.
Base Unit
Configuration
SPM
SPM |
Standard starting and protection relay with VDN board
Power Factor regulation option. Used on motors with SCR exciter
PF
(not recommended for brushless applications)
1.2.2 ACCESSORIES
PG2SPM
: External hardware package for overtemperature and current loss protection up to 200 A
(includes 1-DCCT200 & 1-CM)
PG4SPM
: External hardware package for overtemperature and current loss protection up to 400 A
(includes 1-DCCT400 or DCCT500 and 1-CM)
MPSPM
: Mounting panel to retrofit existing µSPM cutouts for SPM
1
GE Power Management SPM Synchronous Motor Protection & Control 1-
3
1.3 SPECIFICATIONS 1 INTRODUCTION
1.3 SPECIFICATIONS 1.3.1 SPM SPECIFICATIONS
1
PHASE CURRENT INPUTS
CT Primary: 5 to 2000 A
CT Secondary: 5 A
Conversion Range: 0.05 to 6 × CT
Frequency: 50 / 60 Hz
Accuracy: at < 2 × CT: ±0.5% of 2 × CT true RMS
≥ 2 ×
at
CT: ±1% of 6 × CT true RMS
FIELD CURRENT INPUTS
CT Primary: 5 to 1000 A
Conversion Range: 0.05 to 1 × CT
Accuracy: ±2%
EXCITER VOLTAGE INPUTS
Conversion: 0 to 350 V DC (prior to VDN)
Accuracy: ±1%
POWER FACTOR
Range: 0.01 to 1 to –0.01
Time Delay: 0.1 to 10 seconds
Accuracy: ±5%
SWITCH INPUTS (MX & NX)
Type : Dr y c ont a c t
Internal Interrogation Voltage: 85 to 265 V AC (control voltage)
PF ANALOG OUTPUT
Ty pe : Ac ti ve
Output: 0 to 10 V DC max. at R
Accuracy: ±10% (0.1 V)
Isolation: 36 V pk
≥ 1 KΩ (min. load)
L
CONTROL VOLTAGE
Input: 85 to 265 V AC at 48 to 60 Hz
Power: 10 VA nominal
Holdup: 100 ms typical at 120 V AC
RELAY CONTACT
Type : FA R , T RP Form A
FCX Form C
Rated Load: 10 A AC continuous NEMA A300
1 A DC continuous NEMA R300
Break: 10 A at 250 V AC or 30 V DC
Max. Operating Voltage: 250 V AC
ENVIRONMENT
Humidity: 0 to 95% non-condensing
Operating Temp.: –20°C to +70°C
Storage Temp.: –40°C to +85°C
TYPE TESTS
Dielectric Strength: Per IEC 255-5 and ANSI/IEEE C37.90
2.0 kV for 1 min. from relays, CTs, VTs
power supply to Safety Ground
Insulation
Resistance: IEC255-5 500 VDC, from relays, CTs, VTs
power supply to Safety Ground
Transients: ANSI C37.90.1 Oscillography (2.5kV/1MHz)
ANSI C37.90.1 Fast Rise (5kV/10ns)
Ontario Hydro A-28M-82
IEC255-4 Impulse/High Frequency Disturbance,
Class III Level
Impulse Test: IEC 255-5 0.5J 5kV
EMI: C37.90.2 Electromagnetic Interference at
150 MHz and 450 MHz, 10V/m
Static: IEC801-2 Static Discharge
Vibration: Sinusoidal Vibration 8.0g for 72 hrs.
CERTIFICATION
UL: UL listed
CSA: CSA approved
PHYSICAL
Shipping Box: 12.50" × 10.50" × 9.75" (L × H × D)
318 mm × 267 mm × 248 mm (L × H × D)
Ship Weight: 14.25 lb. / 6.45 kg
1-
Specifications subject to change without notice
4
SPM Synchronous Motor Protection & Control GE Power Management
2 INSTALLATION 2.1 OVERVIEW
2 INSTALLATION 2.1 OVERVIEW 2.1.1 DESCRIPTION
The SPM can be incorporate d in synch ronous mot or control equ ipment as a co mplete cont roller (incl uding an
AC power-switching devi ce for the motor starter) or as a field pane l (AC power switching supplied by ot her
device).
2.1.2 ELEMENTS OF A SYNCHRONOUS MOTOR CONTROLLER
A complete synchronou s-m otor contr oller has the ability to s witch the motor on to and off of the power system
and protect the motor from damage that can occur if the motor is running in an abnormal condition such as outof-synchronization.
A complete synchronou s-motor cont roller consist s of a motor starter and swi tching devic e (typically a contactor) which controls the ma in power to the motor. In addition, protectiv e relaying is pro vided for both the sta tor
and the rotor (such as a 469 /SPM com binati on). Con trols for starti ng and st opping the motor (start-s top pushbuttons) are also included. Indicating and metering de vic es such as li ne am met e rs are s upp li ed if no t in cl ude d
in the relays. All of these features are common with motor controllers of all types.
2
Figure 2–1: EXPLODED VIEW OF THE SPM
GE Power Management SPM Synchronous Motor Protection & Control 2-
1
2.2 MECHANICAL INSTALLATION 2 INSTALLATION
2.2 MECHANICAL INSTALLATION 2.2.1 UNPACKING THE SPM
When the SPM is shipped separately, carefully unpack the module and report any observable damage or missing components to the c arrier and to GE Power Management. All inc luded parts are shown in Figure 2–1:
EXPLODED VIEW OF THE SPM on page 2–1.
2.2.2 REMOVING THE DRAWOUT RELAY
2
1. Remove the faceplate as sembl y care fully by pus hing i n on t he qui ck rel ease tab s on t he fro nt of th e SP M
and pulling the faceplate assembly forward. Once the faceplate has pivoted forward, gently lower the faceplate so that it clears the tabs on the bottom of the frame.
DO NOT let the faceplate assembly dangle from the connecting wires.
NOTE
2. Carefully disconnect the ribbon cable from the cradle assembly.
3. Remove the paddle and open the top and bottom lock ing tabs. The relay can n ow be removed from th e
case.
2.2.3 INSERTING THE DRAWOUT RELAY
1. Slide the relay into the case and close the top and bottom locking tabs.
2. Insert the paddle into the opening at the bottom of the relay.
3. Carefully re-connect the ribbon cable to the cradle assembly.
DO NOT shift or skew the ribbon connector.
NOTE
4. Re-mount the faceplate assembly to the case from the front panel. Slide the faceplate onto the tabs on the
bottom of the frame a nd then pivot it up into pos ition over the quick release tabs. The faceplate shoul d
gently snap into place.
2.2.4 MOUNTING THE SPM
Mounting the SPM requires careful attention to the following instructions.
DE-ENERGIZE ALL EXISTING EQUIPMENT BEFORE INSTALLING NEW EQUIPMENT.
CAUTION
1. Remove the relay from the case.
2. Prepare the mounting hole in the panel to dimensions shown in Figure 2–2: PHYSICAL DIMENSIONS.
3. Slide the case into the panel from the front.
4. Install the four mounting scr ews from the re ar of the pane l. The case is now secur ely mounte d and ready
for panel wiring.
2.2.5 SPM MOUNTING ACCESSORIES
See Chapter 8: ACCESSORIES for physical dimensions and mounting requirements.
2-
2
SPM Synchronous Motor Protection & Control GE Power Management
2 INSTALLATION 2.2 MECHANICAL INSTALLATION
2
SPM Sync. Protection/Control
Figure 2–2: PHYSICAL DIMENSIONS
GE Power Management SPM Synchronous Motor Protection & Control 2-
3
2.3 ELECTRICAL INSTALLATION 2 INSTALLATION
2.3 ELECTRICAL INSTALLATION 2.3.1 DESCRIPTION
Wire the SPM using one of the following wiring diagrams (one each for brushless, collector ring, and brushless
and collector ring). Pay particular attention to the CT and PT inputs. These inputs must be connected as shown
below for proper power factor protection.
2
NOMENCLATURE
CM
DCCT
M
OL
T1, T2, T3
FIELD CURRENT CALIBRATION MODULE
DIRECT CURRENT CT
MAIN CONTACTOR
OVERLOAD RELAY
MOTOR TERMINALS
OPTIONAL ACCESSORIES
NOTES:
1) Relays shown with no control power applied to relay
*
2) Trip Relay closed during normal operation
TYPICAL BRUSHLESS MOTOR CONNECTION
A
B
C
B1
I2S
PHASE CURRENT INPUT
B2
B3
B4
I3T
I3S
I2T
T1
T2
SYNC
MOTOR
T3
V+
F
V-
F
V+
E
VOLTAGE
V-
EXCITER/FIELD
E
A18
A19
A21
A20
EF1
FIELD
EF2
VOLTAGEDIVIDER
NETWORK (VDN)
(E+)
(E-)
DCCT
(V+)
(V-)
FC FC
R
SUPPLY
A
B
C
STOP
OL
M
START
M
EXCITER
CONTACTOR
FIELD
CONTACTOR
M
MX
MAIN
AUXILIARY
RM
FC
V
B9
1
V
B10
2
G1
CHASSIS GROUND
B8
FILTER GROUND
A23
TRIP1
A22
TRIP2
FCX
A13
N/O
A14
COM
FCX
A15
N/C
FAR 1
A7
FAR 2
A6
GE POWER MANAGEMENT
SPM
TYPICAL COLLECTOR RING MOTOR CONNECTION
T1
T2
SYNC
MOTOR
T3
V+
F
V-
F
V+
E
VOLTAGE
V-
EXCITER/FIELD
E
A18
A19
A21
A20
REF.VOLT.
CONTROL
POWER
PHASE C
B1
B2B4B3
I2S
I3S
I2T
PHASE CURRENT INPUT
GE POWER MANAGEMENT
I3T
SPM
*
(FAR)
(FCX)
TRIP
CONTACTOR AUX.
APPLICATION
FIELD
FIELD
OUTPUT RELAYS
DIGITAL INPUTS
FIELD
OPTIONAL
REF.VOLT.
CURRENT
I+
V
I-
A24
A25
V
2EXT
1EXT
EE
A5
POWER
A4
MX
MONITOR
VOLTAGE
REDUCED
RS485
COMM
FACTOR
OUTPUT
MX
MX1
NX2
NX1
GND
N-
A11
A12
A9
A10
A1
-
+
A2
A3
A17
N+
A16
FIELD CONTACTOR
F1
FIELD
F2
VOLTAGE DIVIDER
NETWORK (VDN)
(+)
()
(E+)
(E-)
M
ON REDUCED VOLTAGE
STARTERS, REMOVE
JUMPER AND CONNECT
A NO. AUX CONTACT
FROM THE FINAL STEP
CONTACTOR HERE.
PF ANALOG OUTPUT OR
PF REG CONTROL SIG
OUTPUT (IF PF
REGULATOR OPTION)
(V+)
(V-)
(R1)
(F2)
7
CM8CM
DISCHARGE
RESISTOR
CONTACTOR
FIELD
FIELD
+
-
DCCTDCCT
EXCITER
V-
FC
FC
V-V-
EXCITER
RM
TO EXCITER
POWER SUPPLY
TO PLC
OR COMPUTER
EXCITER
FC
V+V+
V+
2-
USED FOR SEPARATELY
SUPPLIED POWER FACTOR
65
240 VAC
1
120 VAC
3
FIELD CURRENT
CALIBRATION
MODULE (CM)
2
4
7
8
REFERENCE VOLTAGE
(OPTIONAL CONNECTION)
BRUSHLESS & COLLECTOR RING - 701756AN.CDR
COLLECTOR RING - 701751.DWG
BRUSHLESS - 701753.DWG
Figure 2–3: TYPICAL WIRING DIAGRAM
4
SPM Synchronous Motor Protection & Control GE Power Management
2 INSTALLATION 2.3 ELECTRICAL INSTALLATION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
FRONT VIEW
QUICK RELEASE TABS
Used to remove display for easy
GE KEY
Used to enter or exit the different
modes of the SPM. These are
Standby, Test, Statistics and
Programming modes.
LOCKING PROVISION
A wire lead seal can be used to
prevent unauthorized removal
of relay.
ENTER KEY
Used to make a selection or acts
as an enter key.
DISPLAY FUNCTION MENU
Menu of all accessible setpoints
and actual values for easy reference.
SPM Sync. Protection/Control
ENTER
DISPLAY FUNCTIONS
Items in and white come standard.green
Items in yellow are optional.
Items in green are motor type dependent.
DISPLAY SCROLL SETPOINT SCROLL
AC Amps
Power Factor
DC Amps
DC Volts
(Exciter) Field Ohms
Power Factor Trip
Power Factor Trip Delay
Power Factor Suppression
Power Factor Mode
FAR Delay
FCX Delay
SCROLL
CONTRAST
access to drawout.
LCD DISPLAY
Back lit 32 character display for
setpoints, actual values and status.
Programmable auto scan sequence
for unattended operation.
SCROLL KEYS
Used to scroll through the various
menus and change setpoint
parameter values.
CONTRAST DIAL
Lightens or darkens display.
2
S1 CASE
Compact S1 rugged metal/bakelite
case. Fits standard cutout.
STATSCROLL
Motor Hours
ISP Trip Ctr
FLP Trip Ctr
PO Trip Ctr
Resync Ctr
NO V Trp Ctr
Exc Trip Ctr
PF Trip Ctr
SCP Trip Ctr
FOT Trip Ctr
AC CT Rating
Full Load Amps
Locked Rotor Amps
Sync. Slip
Stall Time
Run Time
DC CT Primary
High (Exciter) Field Ohms
(Exciter) Field Amps
(Exciter) Field Volts
Incomplete Sequence Delay
Regulator Power Factor
Regulator Gain
Regulator Stability
Regulator Output
Regulator Floor Volts
REAR VIEW
F
FCX COM
E
FCX N/C
15
16
TRP1
V+
I+
V-
V+
19
21
23
25
20
22
24
E
E
F
I-
V-
TRP2
FILTER
GND
N+
17
18
N-
1
1
RS485-
2
1EXT
MX
FCX N/O
FAR1
RS485 GND
NX2
V
3
5
7
9
11
4
13
6
8
10
12
14
A
2345678910111213141516171819202122232425262728
NC
A
RS485+
I2S I2T I3S I3T
B
1 23 4 5678910
NX1
2EXT
V
MX1
FAR2
PULLDOWN DOOR
Hides menu when not in use.
TERMINAL BLOCK A
RELAYS
INPUTS
E
NC
27
26
28
NC
NC
V
V
1
2
OUTPUTS
TRIP: Normally open,
failsafe trip relay.
FAR: Field application
relay.
FCX: Autoloading of the
motor.
EXCITER: Exciter voltage
inputs. Connected via
DCCT and CM.
FIELD: DC field voltage
input.
REDUCED VOLTAGE:
Contact input for
reduced voltage starting.
Motor "ON" input.
Exciter current input.
Power Factor reference
voltage (for seperately
powered option).
POWER FACTOR:
0-10VDC analog signal.
MOTOR LINE CURRENT
2 Phase current inputs.
Accept #8 wire.
CONTROL POWER
85 to 265VAC.
701750AF.CDR
Figure 2–4: PANEL AND TERMINAL LAYOUT
GE Power Management SPM Synchronous Motor Protection & Control 2-
5
2.3 ELECTRICAL INSTALLATION 2 INSTALLATION
2.3.2 GROUNDING
The SPM relay must be sol idly gro unded to a su itable syste m ground. Ex tensi ve filt ering and tr ansie nt protection has been built into the SPM to ensure proper and reliable operation in harsh industrial environme nts.
Proper grounding of the chassis ground terminal is critical to en-sure safety and filtering.
2.3.3 FIELD AND EXCITER VOLTAGE INPUTS
2
The field voltage i nputs (V
via the supplied voltage divider network (VDN).
DO NOT ATTEMPT TO START THE MOTOR WITHOUT THE EXTERNAL RESISTOR ASSEMBLY
WIRED. SEVERE DAMAGE TO THE SPM MAY RESULT IF THE EXTERNAL RESISTOR ASSEM-
CAUTION
The following is a description of the relay outputs.
1. TRIP: Trip Relay. This relay is normally energized and drops out on loss of power or when the modul e
2. FAR: Field Application Relay. This relay picks up at the proper time to apply DC to the motor field.
BLY IS NOT PROPERLY CONNECTED.
senses an abnormal condition.
+ and VF–) and exciter v oltage in puts (VE+ and VE–) are connected to t he relay
F
2.3.4 RELAY OUTPUTS
3. FCX: Loading Relay. This relay picks up when the motor is fully synchronized and ready to be loaded. It is
controlled by the "FCX Delay" programmable setpoint.
2.3.5 CURRENT TRANSFORMER INPUT
The SPM is designe d to work fro m a fiv e a mpe re (5 A) current trans forme r ( CT) s econdary. The current transformer must be connected i n the prope r motor ph ase. Se e Figur e 2–3: TYP ICAL WI RING DIAGRA M on pag e
2–4 to determine proper phase. For brushless applications, the SPM requires inputs from two motor phases.
2.3.6 POWER FACTOR OUTPUT
This output is a 0 to 10 V DC signal that corresponds linearly to phase shift, and sinusoidal to motor power factor. 0 V is zero lagging power factor, 5 V is unity power factor, and 10 V is zero leading power factor.
Calibration: 1 volt change corresponds to an 18° phase shift (not available with power factor regulation). Do not
connect less than 1000 Ω to this output.
2.3.7 DC FIELD CURRENT INPUT
DC field input must be sensed from a separately purchased DCCT (Direct Current, Current Transformer) and
CM (Calibration Module).
2.3.8 EXCITER VOLTAGE OUTPUT MONITOR
The output of the field exciter must be connected to the SPM through a separate resistor when exciter voltage
failure protection and/or exciter voltage display is required.
2-
6
SPM Synchronous Motor Protection & Control GE Power Management
2 INSTALLATION 2.3 ELECTRICAL INSTALLATION
2.3.9 POWER FACTOR REGULATION OUTPUT
This optional output replaces the power factor analog signal output. It consists of a 0 to 10 V DC control signal
which is used to control an SCR Variable Exciter output to obtain motor power factor regulation.
2.3.10 CONTROL VOLTAGE
If control voltage ex cursions occur ou tside the r ange of 85 to 265 VAC, a p rovision is avai lable that will allow
the user to connect a n external stabilizing transf ormer for operation with sev ere control power voltage di ps.
The SPM has separate inputs for control power and power factor reference voltage. This allows connection for
control power from a stabi lized vol tage sour ce of 115 V AC or 230 V AC . Terminal points "V
1EXT
" and "V
2EXT
have been added to accommodate the separate PF reference voltage.
2.3.11 EXTERNAL VOLTAGE PF REFERENCE
When terminal poi nts "V
1EXT
" and "V
" are used to accommod ate a separate PF reference voltage, as
2EXT
described above, a s tandard p rotective function wil l alert the user sho uld this external voltage d rop below th e
acceptable limits for the SP M power s upply. This protection will not allow th e motor t o start while the external
voltage is missin g, bu t the SP M will no t re qui re a r es et befo re the moto r can be restarted. If the exter nal refer ence voltage is lost while the moto r is running, the SPM will trip the motor and will require a r eset before the
motor can be restarted. "MISSING VOLTAGE!" will be displayed until reset.
2
"
Figure 2–5: REFERENCE VOLTAGE INPUT CONNECTIONS
GE Power Management SPM Synchronous Motor Protection & Control 2-
7
2.3 ELECTRICAL INSTALLATION 2 INSTALLATION
2.3.12 RS485 COMMUNICATIONS PORT
One two-wire RS485 po rt is provided. Up to 32 SPMs can be da isy-chained together on a communica tion
channel without excee ding the driv er ca pabil ity. For larger systems, additiona l serial channels mu st be added.
It is also possible to use commercially available repeaters to increase the number of relays on a single channel
to more than 32. Suitable cable should hav e character istic impe dance o f 120Ω (e.g. Belden #9841) and total
wire length should no t exceed 400 0 ft. Commercial ly available repeaters wil l allow for trans mission distanc es
greater than 4000 ft.
2
Voltage differences between remote ends of the communication link are not uncommon. For this reason, surge
protection device s are internally install ed across all RS485 term inals. Internally an iso lated power supply is
used to prevent noise coupling. To ensure that all devices in a daisy-chain are at the same potential, it is imperative that the common ter minal s of eac h RS485 por t are tied to get her and gr ounded only once , at the ma ste r.
Failure to do so may result in intermittent or failed communications. The source computer/PLC/SCADA system
should have similar tr ansient protection devices insta lled, either internally or externally, to ensure maximum
reliability. To avoid ground loops, ground the shield at one point only as shown below.
Correct polarity is also essential. SPMs must be wired with all '+' terminals connected together, and all '–' terminals connected together. Each relay must b e dai sy -ch ain ed to th e next on e. Avoid star or st ub c onne ct ed c onfigurations. The last device at each end of the daisy chain should be terminated with a 120Ω, ¼ watt resistor in
series with a 1 nF capacitor across the '+' and '–' termi nals . Observi ng thes e guidel ines will res ult in a r eli able
communication system immune to system transients.
2-
Figure 2–6: RS485 WIRING
8
SPM Synchronous Motor Protection & Control GE Power Management
3 SYNCHRONOUS MOTOR APPLICATIONS 3.1 OVERVIEW
3 SYNCHRONOUS MOTOR APPLICATIONS 3.1 OVERVIEW 3.1.1 GENERAL
The most attractive and widely applied method of starting a synchronous motor is to utilize squirrel cage windings in the pole faces of the synchronous motor rotor. The presence of these windings allows for a reaction (or
acceleration) torque to be dev eloped in the rotor as the AC excited stator windings induc e current into the
squirrel cage windings . Thus, the synchronous motor starts as an induction motor. These rotor windings are
frequently referred to as damper or amorti sseur windings. The other major function of these winding s is to
dampen power angle oscillations after the motor has sync hronized. Unlike induction motor s, no continuous
squirrel cage torque is developed at normal running speeds. Examine the figure below:
3
Figure 3–1: SALIENT POLE SYNCHRONOUS MOTOR
When the motor accelerates to near synchronizing speed (about 95% synchronous speed), DC current is introduced into the rotor f ield winding s. This c urrent create s const ant polar ity pole s in the roto r, causing the motor
to operate at synchronous speed as the rotor poles "lock" onto the rotating AC stator poles.
Torque at synchronous speed is derived from the magnetic field produced by the DC field coils on the rotor linking the rotating field produced by the AC currents in the armature windings on the stator.
Magnetic polariza tion of the r otor iron i s due to the rotor ’s physical sha pe and arrang ement and the constant
potential DC in coils looped around the circumference of the rotor.
Synchronous motors possess two general categories of torque characteristics. One characteristic is determined by the squirrel- cage design, which prod uces a torque in rel ation to "slip" (some spe ed other than synchronous speed). The other char acteristic is d etermined by the flux in the s alient field pol es on the roto r as it
runs at synchronous speed. The first characteristic is referred to as
istic is usually referred to as
In starting mode, the syn chronou s motor sali ent pol es are not ex cite d by their external DC sour ce. At temptin g
to start the motor with DC applied to the field does not allow the motor to accelerate. In addition, there is a very
large oscillating to rque component at sl ip frequency, produced by field excitation, wh ich could result in motor
damage if full field curre nt is applied during the entir e starting sequence. Th erefore, application of DC to th e
field is usually delayed until the motor reaches a speed where it can be pulled into synchronism without slip.
At synchronous speed, the ferro-magnetic rotor poles become magnetize d, resulting in a small torque (reluctance torque) which enab les the motor to run at very l ight loads in synchronism without external excitation.
Reluctance torque can also pull the motor into step if it is lightly loaded and coupled to low inertia.
synchronous torque
.
starting torque
, while the second character-
It is convenient to make an analogy of a synchronous motor to a current transformer for the purpose of demonstrating angular relationship of field current and flux with rotor position.
GE Power Management SPM Synchronous Motor Protection & Control 3-
1
3.1 OVERVIEW 3 SYNCHRONOUS MOTOR APPLICATIONS
If
I
is an equivalent current in the st ator causi ng the tra nsformer a ction, then
1
I
), and the flux w il l be 90° behind
FD
as the induced field current
rent. See the figure below.
3
I
will be about 180° fr om
I
. Very significantly, then, the poin t of maxim um-i nduce d flux (Ø) oc curs
I
FD
FD
passes through zero from negative to positive; maximum rate of change of cur-
1
I
2
(or
Figure 3–2: TYPICAL TRANSFORMER ROTOR FLUX AND CURENT (CONSTANT SLIP)
The rotor angle at which
I
1
and
I
go through zero depe nds upon the reactance-to -resistanc e ratio in the field
2
circuit. A very high v alue of reactance-to-resistance shifts the angle toward –90°. Re actance is high at low
speed (high frequen cy). At high speed (low slip, l ow frequency), reactance decrease s and the angle shifts
toward 0° if the circuit includes a high value of resistance. As the stator goes beyond –45°, the torque
increases (due to increased stator flux ). At this point,
I
yields a convenient in dicator of maximum flux an d
FD
increasing torque from which excitation is applied for maximum effectiveness.
If the field discharge loop is ope ned at the poi nt of m ax im um flux , thi s f lux is "t rappe d." App ly ing ex ter na l exc i-
tation in correct polarity to increase this trapped flux at this instant makes maximum use of its existence. At this
point the stator p ole ha s jus t mov ed by an d is in po sitio n to pu ll the roto r for ward int o sy nchr onous align ment.
See the figure below.
3-
Figure 3–3: TYPICAL ROTOR FLUX AND CURRENT AT PULL-IN
2
SPM Synchronous Motor Protection & Control GE Power Management
3 SYNCHRONOUS MOTOR APPLICATIONS 3.1 OVERVIEW
Figure 3–4: ANGULAR DISPLACEMENT OF ROTOR
It has been established that salient-pole torque near synchronous speed is a function of both slip and field-discharge resistance. The combi ned e ffects of c age to rque and sal ient p ole tor que for a ty pical m otor a re show n
below. The effect of a higher value of discharge resistan ce on a me dium-tor que mot or are sho wn in Figure 3–
6: FIELD DISCHARGE RESISTANCE – MEDIUM STARTING TORQUE. Obviously, without salient-pole torque
the motor would cease to accelerate certain loads at some point on the speed axis.
3
HIGH-STARTING-TORQUE MOTORMEDIUM-STARTING-TORQUE MOTOR
Figure 3–5: MOTOR TORQUE VS. SPEED
The upper limit of t he dischar ge res ista nce i s gover ned b y the other fu nctio n o f the resist or, which is reduc ing
field voltage to saf e le ve ls dur i ng st arti ng. A s the d is ch arge r es i sta nc e in cr ea se s s o d oes the ind uc ed v ol tage ,
and at some poin t this voltage would be damag ing to insula tion o r oth er com pone nts in the fie ld c ircuit. Solidstate excitation a nd control components in the fiel d circuit have had the effect of makin g the disc harge resi stance and its voltage effect mor e signifi cant. There i s a grea ter sens itiv ity to fie ld vol tage to leran ce le vels wit h
solid-state components.
GE Power Management SPM Synchronous Motor Protection & Control 3-
3
3.1 OVERVIEW 3 SYNCHRONOUS MOTOR APPLICATIONS
3
Figure 3–6: FIELD DISCHARGE RESISTANCE – MEDIUM STARTING TORQUE
Selection of the value of the field discharge resistance is a decisi on that may r equire judici ous applica tion of
several factors present on a particular drive, such as torque, excitation systems, and control components.
The importance of speed for app lying field cannot be over-emphasized. Rotor and load masses cannot be
accelerated fast enough to allow synchronization, if slip is in excess of ten percent.
Synchronous-motor controllers which can acc urately apply field at an optimum speed and a favor able angle
permit matching the motor to the load with a greater degree of precision than might otherwise be possible. The
increase in load w hich can be pulled in due to preci sion applic ation of fie ld will va ry from one m otor design to
another along with system inertia.
Applying excitation at the point of zero induced current (favorable angle) takes advantage of motor capability in
two ways:
1. It catches (“traps”) salient- pole flux at s ignificant ma gnitude (p rovided ther e is a field di scharge re sistor of
adequate value) and uses it for torque during a 180° acceleration period.
2. It catches the rotor in correct angular position to be pulled forward into step.
In addition to permitting closer matching of motor to load, optimum application of excitation also reduces power
system disturbance w hich o ccurs when th e motor go es thr ough a comp lete sli p cycle with the fi eld en ergized .
If the motor is large relative to the power system, surges transmitted to the system will be at a minimum if field
is applied to prevent slip at pull-in.
3-
4
SPM Synchronous Motor Protection & Control GE Power Management
3 SYNCHRONOUS MOTOR APPLICATIONS 3.2 COLLECTOR-RING MOTORS
3.2 COLLECTOR-RING MOTORS 3.2.1 STARTING AND SYNCHRONIZING
Control functions for starting the synchronous motor include the following:
• Applying power to the stator; at full voltage or reduced voltage.
• Shunting the field with a discharge resistor (FDRS).
• Sensing rotor speed.
• Sensing rotor angle.
• Applying excitation at optimum speed and angle.
• Reluctance torque synchronizing.
The first step in starting a synchronous motor is to apply power to the stator by means of a magnetic contactor
or circuit breaker.
Shunting a resistor around the motor field during starting is accomplished with a field contactor. Optimum appli-
cation of excitation (that is, closing the field c ontactor) requires accurate sen sing of motor speed and rotor
angle. This SPM pro vides this functi on. Optimum spee d for pull-in var ies with motor d esign and with the field
discharge resisto r val ue. A dju st men t of the c ontrol to app ly fiel d at v ario us v al ues of mot or spe ed is important.
The correct rotor angle for fiel d application does not vary and is always the po int where induced field cu rrent
passes through zero goi ng f rom ne gative to positive – the poi nt o f ma xi mu m r oto r flux ( see Figure 3–3:: TYPICAL ROTOR FLUX AND CURRENT AT PULL-IN on page 3–2). Maximum utilization of motor pull-in capability
depends upon the degree to which the control can accurately sense speed and rotor angle.
Rotor frequency is th e mo st pos iti ve el ec tr ical parameter available for in dica t ing sp eed , and ca n be s en se d by
detecting the frequency of the voltage across FDRS . Voltage across FDRS is not actually "induced field voltage," but is the volta ge which is essenti ally in time phase relation to the curr ent through the re sistor. That is,
the current goes through zero at the same time the voltage goes through zero.
The SPM detects the proper rotor speed (PRS ) and rotor angle (PRA) signal, implemente d in the Field Programmable Gate Array (FPG A). Outputs fr om the PRS and the circuits are used to de termine the proper time
to close the Field Appli cation Relay (FAR), based on the pe rcent synchrono us slip setpoi nt. When the pro per
rotor speed and the proper rotor angle conditions are met as determined by the FPGA, the CPU delivers a signal to the FAR Relay so it can close its contact FAR1-F AR2. FAR picks up field contactor FC to apply excitation
to the motor field and to o pen the fie ld d isc har ge resi st or loo p. S ee Figu re 2–4 : PANEL AND TERMINAL LAYOUT on page 2–5 for details. The speed at which the motor is to synchronize (PRS) can be programmed from
90 to 99.5% of synchronous speed.
3
GE Power Management SPM Synchronous Motor Protection & Control 3-
5
3.2 COLLECTOR-RING MOTORS 3 SYNCHRONOUS MOTOR APPLICATIONS
3.2.2 RELUCTANCE TORQUE SYNCHRONIZING
A lightly loaded syn chro nou s m otor c onn ected to a low inertial load may pul l i nto sy nc hroni s m be fore the rotor
poles are externally magnetized. This is commonly known as reluctance torque synchronizing. This magnetization can result in su fficient torque to hol d the salient poles in direct align ment with corr esponding st ator poles
and run the motor at sy nchronous speed. However, when load is applied, th e rotor begins to slip since th e
torque developed is o nly a fraction of rate d torque under sep arate excitation. Fu rthermore, the rotor is polarized by the stat or flux u nder this condition and can therefore be polar ized in a ny direc t axis al ignment; occurring each 180°. External excitation forces pole-to-pole alignment in only one orientation of the direct axis.
Should the rotor pull in to syn chronism 180° away from the normal running al ignment, external ex citation will
build up rotor flux in opposition to the stator flux. As the external excitation builds up, correct alignment of rotor
to stator occurs by slipping one pole and the motor will then run in normal synchronism.
3
The Field Application Control must respond in such a way as to proceed with proper application of excitation in
the event the motor does synchronize on reluctance torque. The following diagram demonstrates how the SPM
automatically responds to reluctance torque synchronizing.
CORRECT
ORIENTATION
180°
DISORIENTATION
3-
Figure 3–7: RELUCTANCE TORQUE MOTOR MAGNETIZATION
6
SPM Synchronous Motor Protection & Control GE Power Management
3 SYNCHRONOUS MOTOR APPLICATIONS 3.2 COLLECTOR-RING MOTORS
3.2.3 STARTING PROTECTION
The amortisseur, or cage winding of a synchronous motor, is probably the element most susceptible to thermal
damage. Its function is essen tially operative onl y during starting, a nd there are limitations on sp ace available
for its construction on to the rotor. Hence, it is usually made of lighter material than the cag e winding of an
induction motor. The cage is also vulnerable to overheating should the motor be allowed to run out of synchronism with no excitation. In this case, it runs as an induction motor at some value of slip which will produce cage
current that develops r unning torque . However, the cage of a synchronous m otor is not designed for continuous operation. Theref ore, an important protective function of t he controller is to prevent overheating o f the
cage winding both during starting and running out of synchronism.
Monitoring the starting c ondition of a sync hronous motor can be accom plished by lookin g at the frequency of
induced field current, the same procedure used to ac complish sy nchroniz ing. Motor desig ners always plac e a
limit on the time a particul ar motor can be allowed to remain stalled (" allowable stall time"). An acceler ated
schedule can then be established for the motor in terms of running time at any speed less than synchronous as
a percent of allowab le stall time. Increased air circulation from th e rotor fan reduces the heating rate as the
motor accelerates . Frequency can b e measured d irectly as an indication of s peed, and the des igner's curves
for speed versus time c an be used for protection by softwa re that in tegrates the time-speed function. The figure below shows the typical cage heating protection characteristics during acceleration.
The time-speed functi on show n in belo w is d etermine d inter nally b y SPM s oftwar e. The mo tor spee d is d etermined from the induced field voltage frequency. The programmed values for maximum allowable stall time and
50% speed run time determine which characteristic of protection is required from the family of curves.
3
The SPM will cause a TRIP operation and display "SQL CAGE TRIP" if it calculates that the thermal limit of the
cage winding is reached. The SPM will also p revent an attempted restart if it calculates, from lear ned start
experience, that the cage winding has not had sufficien t cooling time to allow a su ccessful st art. In this case
the message "START INHIBITED! Ready in xxx min" will be displayed
200
150
100
80
60
50
40
30
25
20
15
10
Run Time
Allowable Zero Speed Stall Time
1.5
8
6
5
4
3
2
3
2.05
1.46
1.05
0
0
.
1
0
10 20 60 90 1008070504030
% Synchronous Speed
701761A7.CDR
Figure 3–8: AMORTISSEUR WINDING PROTECTION
GE Power Management SPM Synchronous Motor Protection & Control 3-
7
3.2 COLLECTOR-RING MOTORS 3 SYNCHRONOUS MOTOR APPLICATIONS
3.2.4 REDUCED VOLTAGE STARTING
Many synchronous mot or starti ng applications involve either reduced voltage (starting reactor or autotransformer) or part-winding star ting me thods. When these m ethods are use d, the avail able torq ue for ac celera tion
is reduced from the torque that would result from a full-voltage start. Also, the allowable stall time of a motor is
extended during a reduced-voltage start due to the reduced heating-rate resulting from lower inrush currents.
The SPM has the abilit y to take advantage of the motor's extended st all time so that the mot or and load can
accelerate to synchrono us speed in a time period longer than would be allowed with a full volta ge start. The
acceleration torque is reduced as the square of the ratio of reduced voltage to full voltage, and the motor-heating rate is proportional to the square of the starting current. Si nce the motor inr ush current i s reduced p roportionally with the voltage reduction (due to the constant impedance of the synchronous motor at stall) the
following allowable stall time factor applies:
3
2
I
PLR
----------- -
I
MLR
where:
I
= programmed full voltage locked rotor current.
PLR
I
= measured inrush current.
MLR
This ratio can be used as a factor for increasing the stall time above the full voltage allowable stall time for any
given speed. See Figure 19.
The SPM calculates the ratio, squares it, and factors this value into the stall time algorithm approximately onetenth of a second after m otor star ts. When the fin al ste p conta ctor cl oses and appli es ful l voltage to the mo tor
windings, a N.O. interlock from this contactor is wired to the SPM to signal that the motor is now at full voltage.
The correction factor for reduced voltage starts then immediately becomes unity.
If, for any reason, it is not desirable to have this ratio correction factored in , a jumper may be placed ac ross
inputs NX1 and NX2. Conver sely, if the motor is star ted from a weak s ystem, and signific ant vol tage dips are
expected during starting , the factory jumper from NX1 to NX2 may be remove d. The SPM will automatical ly
extend the stall and accelerating time per the reduced voltage factor.
To find the protective characteristic used, plot the programmed value for 50% run time and
draw in the complete curve through the plotted point using the above curves as a guide.
NOTE
The curves shown in the following diagram demonstrate how the trip characteristic of the
amortisseur winding protection is adjusted for reduced voltage starts. For this example, curve
NOTE
1 is taken from one of the family of curves in Figure 3–8: AM ORTISSEUR WINDIN G PROTECTION on page 3–7.
3-
8
SPM Synchronous Motor Protection & Control GE Power Management
Loading...