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SMC-250 Synchronous Motor Controller
System Overview
+1 618.654.2341 (USA)
INTRODUCTION
The Basler Electric SMC-250 Synchronous Motor
Controller precisely and reliably controls the level of
excitation power supplied to the field of a brushless
synchronous motor. Field excitation power is
delivered and controlled by a DECS-250 Digital
Excitation Control System. Comprehensive motor
protection is provided by a BE1-11m Motor Protection
System. Coordinated programming of the DECS-250
and BE1-11m yields efficient control of the machine
and minimizes machine downtime.
The DECS-250, BE1-11m, control relays, and
connection terminals are mounted and wired on a
single mounting plate or pan chassis intended for
installation in a suitable enclosure.
This publication serves as an overview of the
functions and capabilities available in the SMC-250.
System drawings and product documentation specific
to the devices of the SMC-250 accompany this
publication.
SAFETY
HANDLING AND MAINTENANCE
Careful handling and routine maintenance will
promote SMC-250 longevity and preserve its
performance. Basler Electric publication 9410100990,
supplied with this publication, provides guidelines for
handling, installing, and maintaining the SMC-250.
EQUIPMENT OVERVIEW
SMC-250 features and options are defined and
specified by a style number derived from the style
chart shown in Figure 1.
Standard equipment elements include a DECS-250
Digital Excitation Control System, BE1-11m Motor
Protection System, BE3-74SD DC Millivolt Sensing
Relay (for overexcitation and underexcitation
protection), auxiliary relays, a metering shunt, dc
power supply, circuit breakers, and user terminals.
Mounting Configurations
One of two SMC-250 mounting configurations may
be specified. Components are mounted and wired on
a mounting plate (style xxxxxxMx) or a pan chassis
(style xxxxxxPx).
Warning!
Personal injury may result if contact is made
with system components carrying high
voltages. The circuit diagrams, supplied with
this document, will disclose hazardous areas.
As with all electrical equipment, appropriate safety
measures must be taken whenever dealing with the
excitation equipment. High v oltag es are present at
the equipment. The voltage magnitudes depend upon
the characteristics of a particular system. Opening
the power source connections does not completely
remove the threat of high voltages. As long as the
machine is physically connected to the system, the
possibility of a safety hazard exists.
When working with the excitation control switchgear,
every precaution must be taken to ensure that all
high voltages are isolated and avoided. In addition to
voltage at the PPT, there may be other power
sources connected to the equipment. These sources
may include the user-supplied dc control power and
the ac station power. Consider all connections to be
live and dangerous until proven otherwise .
The mounting plate is constructed from 1.5 millimeter, galvanized steel. Mounti ng pla te dim ens ions
are shown on an outline drawing which accompanies
this publication.
The pan chassis is constructed from 11 gauge steel
and finished with a light-gray, thermoset polymer
coating. Pan chassis dimensions are shown on an
outline drawing which accompanies this publication.
Terminal Configurations
One of two SMC-250 terminal configurations may be
specified. User connections to the SMC-250 are
made with spring terminals (style xxxxxxxS) or
compression (screw) terminals (style xxxxxxxC). Both
terminal types accommodate wire sizes over the
range of 24 to 12 AWG or 0.2 mm
2
to 2.5 mm2. When
wiring to spring terminals or compression terminals a
wire insulation stripping length of 8 to 10 millimeters
(0.315 to 0.394 inches) is recommended.
When tightening the connection screws of
compression terminals, apply a torque no greater
than 0.6 N•m or 5.3 in-lb.
Control and Indication
SMC-250 controls consist of user-supplied switches
and contacts which connect to the plate/chassis
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terminals. Switch and contact inputs are commonly
used for start and stop control of the SMC-250,
setpoint adjustment, and operating mode control.
System indications are prov ided throu gh outp ut
contacts from the DECS-250, BE1-11m, and BE374SD. Output contact connections are made at the
plate/chassis terminal blocks.
External Accessories
Optional, external accessories include an Analog
Expansion Module (AEM-2020), a Contact Expansion
Module (CEM-2020), an RTD Module, and an
Interactive Display Panel (IDP-800).
Analog Expansion Module (AEM-2020)
DECS-250 inputs and outputs may be augmented
with the following analog inputs and outputs of the
AEM-2020:
• Eight analog inputs
• Eight RTD (resistance temperature detector)
inputs
• Two thermocouple (temperature) inputs
• Four analog outputs
AEM-2020 input and output states are communicated
to and from the DECS-250 via CANbus. Input
thresholds can be configured and programmed using
BESTCOMSPlus
®
and BESTlogic™Plus. Outputs are
intended to drive external, analog meters and can be
configured for indica tio n of motor values and oth er
parameters.
AEM-2020 details and specifications are provided in
the DECS-250 instruction manual (Basler publication
9440300990).
Contact Expansion Module (C EM-2020/CEM-2020H)
The CEM-2020 or CEM-2020H can be specified to
provide the following additional combinations of
DECS-250 contact inputs and outputs:
• Ten contact inputs
• Eighteen contact outputs (CEM-2020H) or
twenty-four contact outputs (CEM-2020)
CEM-2020 input and output contact states are
communicated to and from the DECS-250 via
CANbus. Input and output functions are assigned
using BESTlogic™Plus.
RTD Module
BE1-11m RTD (resistance temperature detector)
inputs, analog inputs, and analog outputs can be
augmented with the available RTD module. The RTD
module provides:
• Twelve RTD inputs
• Four analog inputs
• Four analog outputs
Each RTD input is configurable to protect against
high or low motor temperatures. Programmable over
and under thresholds for the analog inputs can be
used to trigger a protection element within the
BE1-11m. The analog outputs can be configured to
provide real-time metering of individual motor
parameters.
RTD module details and specifications are provided
in the BE1-11m instruction manual (Basler publication
9424200996).
Interactive Display Panel (IDP-800)
A 7.5-inch (19-centimeter) touch-panel can be
installed locally or remotely to:
• View analog and digital system parameters
• Configure motor control, limiter, and pr otec t ion
settings
• Download system data recorded by the
DECS-250
Details about the IDP-800 are available in Basler
publication 9437600990.
SYSTEM ELEMENTS
Interconnected SMC-250 system elements work
together to supply regulated excitation power to the
field and protect the controlled equipment. All
excitation system element c onnecti ons are illust rat ed
on the system interconnection diagrams.
Inputs and Outputs
SMC-250 inputs and outputs consist of power and
sensing inputs, control inputs and outputs, the field
output, and communication ports. For input and
output connections, refer to the appropriate
interconnection diagram provided with this
publication.
Control Power
Control power is determined by the SMC-250 style
number and can be 120 Vac (style xxx1xxxx) or
24 Vdc (style xxx2xxxx). When 24 Vdc control power
is specified, the SMC-250 has a station power input
range of 85 to 264 Vac or 90 to 350 Vdc.
Operating Power
SMC-250 operating power is typically supplied by an
external PPT sized for the application.
Sensing Inputs
SMC-250 sensing voltage and sensing current are
supplied by external VTs and CTs configured to
supply three-phase sensing to the DECS-250 and
BE1-11m. The VTs and CTs must be sized
appropriately for the application and compatibility with
the SMC-250. The CTs may have a secondary rating
of 1 Aac (style xxxxx1xx) or 5 Aac (style xxxxx5xx).
Field Output
To obtain optimum metering resolution of the field
current, one of three field output ranges may be
specified to suit the application requirements, an
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excitation current range of 1 to 4 Adc is specified by
SMC-250 style xxxxAxxx, and excitation current
range of 4 to 8 Adc is specified by style xxxxBxx, or
an excitation current range of 8 to 15 Adc is specified
by style xxxxCxxx.
Control Inputs
SMC-250 control inputs are typically received from
remotely-located control switches and contact inputs
from external devices. The SMC-250 has preprogrammed control inputs that can be configured at the
discretion of the user. Refer to the appropriate
interconnection diagram for contr ol input f uncti ons
and terminal assignments.
Control Outputs
SMC-250 control outputs consist of preprogrammed
output contacts and output contacts available for
configuration by the user. All control output
connections are made at the SMC-250 plate/chassis
terminal blocks. Refer to the appropriate interconnection diagram for control output function and
terminal assignments.
Communication Provisio ns
Optional accessory devices communicate with the
SMC-250 via the Ethernet port of the DECS-250 or
BE1-11m.
Additional communication capability is provided
through an SMC-250 RS-485 communication port
which uses the Modbus™ RTU protocol. RS485
connections are made at plate/chassis terminals
TB1-54 (A), 55 (B), and 56 (shield).
Digital Excitation Control Syste m DECS-250
The DECS-250 supplies regulated excitation power
to the motor field. It also monitors parameters to
control and limit the motor from operating beyond its
capabilities.
Detailed information about DECS-250 operation can
be found in Basler publication 9440300990. The
following paragraphs serve as an overview of DECS250 functions.
Regulation
Digital signal processing and precise regulation
algorithms enable the DECS-250 to accurately
regulate the level of excitation. Motor parameters are
monitored through user-supplied VTs and CTs.
Sensing of field voltage and current is obtained
directly from the field. Depending upon the regulation
mode in use, the DECS-250 compares all or some of
these monitored parameters with the operating
setpoint and provides regulated excitation power to
the field. Two DECS-250 regulation modes are
possible: Manual or Auto.
Manual Mode
In Manual mode, the DECS-250 regulates the level of
excitation power supplied to the field independently of
all motor operating conditions. This makes Manual
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mode useful as a backup method of excitation control
if a loss of motor voltage sensing or current sensing
occurs. In an SMC-250 system, Manual mode is
configured for field current regulation (FCR). FCR is
selected automatically at system startup or manualy,
by the operator, during normal operation. When
operating in FCR mode, the DECS-250 regulates
only the level of field current. The operator must
manually vary the FCR setpoint in order to achieve
the desired motor operating conditions.
Auto Mode
During the motor startup sequence, the DECS-250 is
switched from FCR to Auto mode when th e BE1 -11m
determines that the level of ac motor current has
reached the nominal level. In Auto mode, the DECS250 measures the real power into the motor and
adjusts the field excitation to obtain the desired level
of reactive power (and power factor).
Auto Tracking
The setpoint of the active regulation mode is
automatically tracked (followed) by the inactive
control modes. This feature enables the initiation of
“bumpless” transfers between Auto and Manual
mode and vice versa. For example, if a loss of
sensing occurs while operating in Auto mode, the
auto tracking function will minimize the disturbance
that the transfer from Auto mode to Manual mode
could cause.
Limiters
As implemented in the SMC-250, the following limiter
functions are enabled in the DECS-250: underexcitation, overexcitation, reactive power (var),
underfrequency/volts per hertz, upper setpoint, and
lower setpoint.
Underexcitation Limiter (UEL)
The DECS-250 compares the real power (kW)
flowing into the motor with the reactive power (kvar)
being supplied. If the reactive power decreases
below the UEL setpoint, the DECS-250 will increase
field excitation to maintain synchronism and avoid
tripping the motor offline. During an under exc itat ion
condition, the DECS-250 closes the SMC-250
General Limiting output contacts at terminals TB1-64
and 65.
If underexcitation persists and is not corrected, the
DECS-250 closes the SMC-250 Alarm output
contacts at terminals TB1-90 and 91.
Overexcitation Limiter (OEL)
If the level and duration of current applied to the field
exceeds the OEL settings, the DECS-250 will retract
further increases in field current and lower the current
to a safe level for the machine. The OEL operates at
three levels to permit short-term var boosting that
could be beneficial for the application. During overexcitation limiting, the DECS-250 closes the SMC250 General Limiting output contacts (TB1-64, 65). If
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overexcitation persists and is not corrected, the
DECS-250 closes the SMC-250 Alarm output
contacts (TB1-64, 65).
Reactive Power (Var) Limiter
The DECS-250 compares the level of motor reactive
power with the user-established var threshold. A var
level outside the established setting initiates var
limiting.
During var limiting, the DECS-250 closes the SMC250 General Limiting output contacts (TB1-64, 65).
Setpoint Limiter
Adjustment of the active DECS-250 setpoint to either
the upper or lower limit will result in a General
Limiting annunciation at SMC-250 terminals TB1-64
and 65.
Alarms Function
DECS-250 system parameters, communication links,
protection functions, and remote inputs/outputs are
continuously monitored for alarm conditions. An
active alarm triggers closure of the DECS-250
General Protection output contacts at plate/chassis
terminals TB1-66 and 67.
Communication
The DECS-250 supports simultaneous Modbus™
communication through its c opper Ether n et por t
(Modbus/TCP) and its RS-485 port (Modbus RTU).
Short-term communication with a PC operating
BESTCOMSPlus
®
.
Operating Logic
In the SMC-250, the DECS-250 is preconfigured with
operating logic that is tailored specifically to
synchronous motor applications. If desired, this logic
scheme can be customized by using the logic
programming capabilities of BESTlogic™Plus. The
BESTlogic™Plus chapter of Basler publication
9440300990 provides information about customizing
DECS-250 logic.
Motor Protection System (BE1-11m)
The BE1-11m provides startup coordination and
power factor protection for the motor. The BE1-11m
enhances motor reliability by providing the following
features:
• Comprehensive protection and control functions
• Standard, IEC, or custom thermal curves which
adapt to thermal, inertia, and voltage conditions
• Accurate metering of motor parameters
• Extensive reporting capabilities: current demand,
watthours, varhours, motor start records, and
motor maintenance data
• Oscillography capabilities can be used to
evaluate motor characteristics (V curves) and
reduce commissioning time
Information about the BE1-11m can be found in
Basler publication 9424200998 (quick-start guide),
9424200996 (device manual), 9424200997
(communication quick-start guide), and 9424200890
(Modbus communication protocol manual).
Startup Coordination
At system startup, a Start contact input is applied to
the BE1-11m which enables DECS-250 excitation
control and prevents an SMC-250 Alarm output from
being issued during startup before the motor reaches
a nominal operating state.
Protection
The SMC-250 is supplied with the BE1-11m
configured for power factor protection. In a
synchronous motor application, power factor
protection prevents the motor from consuming
excessive reactive power (vars). If the var level is
permitted to escalate, a loss of synchronism can
result. A power factor trip closes the contact of
BE1-11m output 8.
Other BE1-11m protection elements can be enabled
and implemented at the user’s discretion.
Communication
The BE1-11m supports simultaneous Modbus
communication through its c opper Ether n et por t
(Modbus/TCP) and its RS-485 port (Modbus RTU).
Short-term communication with a PC operating
BESTCOMSPlus
®
is possible through the front-panel
USB port.
Operating Logic
As implemented in the SMC-250, the BE1-11m
operating logic is preconfigured for basic protection of
the synchronous motor and annunciation of
preselected motor/SMC-250 conditions. If desired,
the BE1-11m logic scheme can be customized by
using the logic programming capabilities of
BESTlogic™Plus. The BESTlogic™Plus chapter of
Basler publication 9424200 996 prov ides infor mat ion
about customizing BE1-11m logic.
DC Millivolt Sensing Relay (BE3-74SD)
The BE3-74SD monitors the level of exciter field
current through metering shunt SH1 and functions as
an overexcitation/underexcitation relay. The
adjustable underexcitation setpoint is preset at 20%
of the full-load excitation current rating. The
adjustable overexcitation setpoint is preset at 110%
of the full-load excitation current rating. A time delay
setting of 5 seconds for both setpoints prevents
nuisance tripping during transient disturbances.
When an underexcitation or overexcitation condition
is detected, the BE3-74SD trips and closes the SMC250 Alarm output contacts. During motor startup,
BE3-74SD tripping is inhibited by the BE1-11m.
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Details about the BE3-74SD are provided in Basler
publication 9320800990.
STARTUP AND SHUTDOWN
SMC-250 startup and shutdown sequences are
described as follows.
Startup
SMC-250 startup should coincide with the application
of a motor start command. Upon SMC-250 startup,
the DECS-250 begins regulating excitation in Field
Current Regulation (FCR) mode.
Startup is initiated through application of a contact
input at terminals TB1-21 and 22 which energizes
Start/Stop Relay K1 and contact IN1 of the BE1-11m.
(Startup cannot occur if the user-supplied lockout
(86) device is tripped.)
When energized, K1 applies operating power from
the external PPT to the ICRM and DECS-2 50 and
applies a Start contact input to the DECS-250. This
enables field current regulation by the DECS-250.
When IN1 of the BE1-11m is energized, it enables the
BE1-11m to close output contact OUT4 when it
senses nominal ac motor current. Closure of OUT4
applies a contact input to DECS-250 IN6. This places
the DECS-250 in Auto mode and enables regulation
of motor power factor. The energizing of BE1-11m
IN1 also initiates an internal BE1-11m time delay
which, during timing, prevents trips related to motor
startup from the BE3-74SD, DECS-250, and
BE1-11m. once the time delay expires, BE1-11m
OUT5 closes and enables the BE3-74SD
underexcitation and overex c itati on outp ut con tac ts ,
DECS-250 underexcitat io n (bac k up) and
overexcitation (backup) output contacts, and BE111m major fault output contacts to close the SMC-250
Alarm output if conditions dictate.
Shutdown
SMC-250 shutdown is initiated through removal of
the Start contact applied at terminal TB1-21 and 22
or a trip of the user-supplied lockout (86) device.
Initiation of an SMC-250 shutdown de-energizes K1
and IN1 of the BE1-11m.
When de-energized, K1 disconnects the ICRM and
DECS-250 from the output of the PPT and applies a
Stop contact input to the DECS-250. This disables
regulation of excitation by the DECS-250.
De-energizing BE1-11m IN1 opens BE1-11m outputs
OUT4 and OUT5. OUT4 switches the DECS-250
from Auto mode to FCR (Field Current Regulation)
mode. OUT5 prevents the BE3-74SD, DECS-250,
and BE1-11m from closing the SMC-250 Alarm
output.
SPARE/RESTORATION COMPONENTS
A reasonable stock of spare parts will minimize
downtime in the event of an equipment malfunction.
A list of recommended spare parts accompanies this
publication.
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Figure 1. SMC-250 Style Chart
Instructions
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