INSTRUCTION MANUAL FOR
83-467-001 Revision B
MODEL
SERIAL NUMBER
LAMBDA EMI
405 ESSEX ROAD, NEPTUNE, NJ 07753
TEL: (732) 922-9300
FAX: (732) 922-9334
TCR 3 Phase OPERATING SYSTEM MANUAL
TABLE OF CONTENTS
I. GENERAL INFORMATION Page
1.1 INTRODUCTION 1
1.2 SPECIFICATION 2
II. INSTALLATION
2.1 INITIAL INSPECTION 6
2.2 POWER REQUIREMENTS 6
2.3 LOCATION 6
III. OPERATION INSTRUCTION
3.1 TURN-ON CHECK OUT PROCEDURE 7
3.1.1 Over-Voltage Output 8
3.2 GENERAL OPERATION 9
3.3 MODES OF OPERATION 9
3.3.1 Normal Operation 10
3.3.2 Remote Sensing 10
3.3.3 Remote Programming 11
3.3.4 Remote Programming by External Resistance 12
3.3.5 Remote Programming by External Voltage 13
3.3.6 Remote Programming by External Current 14
3.3.7 Parallel Programming 14
3.3.8 Parallel Operation - Master/Slave 16
3.3.9 Series Operation 16
3.3.10 Remote Meters 17
3.3.11 Remote Turn-On 17
IV. THEORY OF OPERATION
4.1 GENERAL 19
4.2 POWER FLOW 19
4.3 SIGNAL FLOW 20
4.4 SCR FIRING CIRCUIT 22
4.5 REMOTE TURN-ON 22
4.6 OVERVOLTAGE PROTECTION OPTION 23
4.7 DIGITAL METER A100 PCB 23
V. MAINTENANCE
5.1 GENERAL 24
5.2 INSPECTION AND CLEANING 24
5.3 CALIBRATION 24
5.3.1 Ammeter Calibration 25
5.3.2 Firing Balance 25
5.4 TROUBLESHOOTING
5.4.1 Overall Troubleshooting Procedure 25
5.4.2 Troubleshooting Chart 26
5.4.3 Overvoltage Troubleshooting 28
5.5 PRIMARY DIODE REPLACEMENT 28
5.6 FAN REPLACEMENT 29
3 Phase 15kW addendum 29
LIST OF ILLUSTRATIONS
Figure A: Front Panel Controls and Indicators 7
Figure 1: Normal Operation 10
Figure 2: Remote Sensing 11
Figure 3: Remote Programming by External Resistance, Voltage Mode 12
Figure 4: Remote Programming by External Resistance, Current Mode 12
Figure 5: Remote Programming by External Voltage, Voltage Mode 13
Figure 6: Remote Programming by External Voltage, Current Mode 13
Figure 7: Remote Programming by External Current, Voltage Mode 14
Figure 8: Remote Programming by External Current, Current Mode 14
Figure 9: Master/Slave Power Connection 15
Figure 10: Parallel Operation Master/Slave 16
LIST OF TABLES
Table 1: Rating Table 5
I GENERAL INFORMATION
I.1 INTRODUCTION
This manual contains operation and maintenance instructions covering the TCR 3
Phase Power Supply series manufactured by Electronic Measurements, Inc. of
Neptune, NJ.
All models provide AC turn on/off and circuit protection by means of a UL rated input
circuit breaker. Output control is provided by a 10 turn voltage control and a 1 turn
current control which are monitored by front panel meters. These meters are an
optional selection between either an analog or digital display.
Input AC is applied to 3 pairs of bi-directional connected SCRs placed within the
delta connected primary of the main power transformer. The secondary of this
transformer is rectified and double LC filtered to provide a low ripple DC output. It
also has a dual-amplifier - one for voltage channel and one for current channel. In
addition, it also has adjustment controls that will furnish full rated output voltage at
the maximum rated output current or can be continuously adjusted throughout most
of the output range.
These supplies may also be controlled locally at the front panel or remotely by
external voltage, current or resistance on rear mounted programming terminals.
VOLTAGE PROGRAMMING -
Voltage Programming -
Current Programming -
Resistance Programming -
CURRENT PROGRAMMING -
Voltage Programming -
Current Programming -
Resistance Programming -
0 to 5Vdc
Programs from 0 to full voltage output.
0 to 1mA (into 5000 ohms)
Programs 0 to full voltage output.
0 to 5000 ohms
Programs 0 to full voltage output.
0 to 100mV
Programs 0 to full current output.
0 to 1mA (into 100 ohms)
Programs 0 to full current output.
0 to 100 ohms
Programs 0 to full current output.
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83-467-001 Rev. A
Output voltage and current are continuously monitored by two front panel meters.
Input power is connected to a four screw terminal at the rear of the unit. The output
terminals are heavy busbars mounted on the rear of the unit. A 17 screw terminal
block at the rear of the unit provides expansion of the operational capabilities of the
instrument. A brief description of these capabilities are given below:
I.1.1 remote sensing
Separate output sensing terminals are provided to remotely sense the power supply
output at a distant load. This feature compensates for the voltage drop in the power
distribution system and provides specified regulation at the point of load.
I.1.2 remote programming
The power supply output voltage or current can be controlled from a remote location
by means of an external voltage source or resistance.
I.1.3 parallel operation
The power supply output can be operated in parallel with another unit when greater
output current capability is required. The parallel operation permits one "master"
supply to control the other supplies.
I.1.4 series operation
Two power supplies can be used in series when a higher output voltage is required in
the constant voltage mode of operation or when greater voltage compliance is
required in the constant current mode of operation.
I.1.5 Remote turn on
The power supply may be remotely turned on or off by application of a combination of
external voltages or interlock control. The open interlock potential is the applied
external voltage level. If the interlock function is used without an external control
level the open interlock potential is 24 Vdc.
I.2 SPECIFICATIONS
I.2.1 AC input
Standard AC input is 208/220/230 volts.
A three-phase, three-wire system which will operate within full specification form 190
to 253 volts or optional voltage as specified. Input AC phase rotation sequence is not
critical to this supply.
The phase to phase voltage balance requirement is ± 2% to achieve ripple
specification.
Current Draw Per Phase
at full load
2.5kW Units
5kW Units
10kW Units
AC line current is proportional DC load current.
Page 2 of 29
83-467-001 Rev. A
12 Amps
23 Amps
46 Amps
I.2.2 option aC
All models are available with optional AC inputs of:
INPUTS:
I.2.3 line frequency: 47-63hz
I.2.4 aC inrush
All models are "soft-started" so that during initial activation or reapplication on
interrupted power the input SCRs slowly "phase in" from non-conduction mode.
Since the SCRs are in series with the transformer primary there is no magnetic inrush
current due to core memory.
I.2.5 phase loss
Loss of a phase voltage will inhibit power supply output and illuminate the front panel
phase loss light. The power supply is not damaged when the phase voltage is
restored and normal operation will automatically resume.
I.2.6 regulation
Voltage Mode - For line voltage variations or load current variations within the rating
of the supply, the output voltage will not vary more than 0.1% of the maximum
voltage rating depending upon the unit.
200V ± 10%
380V ± 10%
415V ± 10%
460/480V (414-505V)
400V ± 10%
Current Mode - For line voltage variations or load voltage variations within the rating
of the supply, the output current will not vary more than 0.1% of the maximum current
rating depending upon the unit.
On those units in which the percentage of voltage or current ripple exceeds the
specified regulation, the regulation will appear to be degraded because of the effect
of this ripple on the measurement.
I.2.7 stability
The output voltage or current will remain within .05% of full output for 8 hours after
warm-up under fixed line load and temperature conditions.
I.2.8 transient response
A 30% step increase in power demanded by the load will cause a transient in the
regulation output which will typically recover to within 2% of final value within 75
milliseconds.
I.2.9 temperature coefficient
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83-467-001 Rev. A
Voltage - The temperature coefficient of the output voltage set point is 0.02% per
degree centigrade of the maximum output voltage.
Current - The temperature coefficient of the output current set point is 0.03% per
degree centigrade of the maximum rating of the supply.
I.2.10 ambient temperature
0° C to +40° COperating:
-40° C to +85° CNon-Operating:
Critical circuitry is thermostat protected so that in the event of an over-temperature
condition the unit is turned off until a safe temperature returns.
I.2.11 cooling
All units are air cooled and thermostatically protected. Air enters at the front right
side and exits at the front left side and rear.
I.2.12 ripple
The output voltage ripple specified in the Rating Table is the worst case ripple under
any resistive load condition with the power line within specification. Typically the
highest ripple occurs at 50% output voltage/current and is lower at maximum output
voltage and power is approached. Output ripple voltage and current is 31% higher
than shown when supply is operated at 50Hz line frequency.
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83-467-001 Rev. A
RATING TABLE
OUTPUT RATINGS
@50° C
0-7.5
0-6
0-6
0-10
0-10
0-10
0-20
0-20
0-20
0-30
0-30
0-40
0-40
0-40
0-50
0-80
0-80
0-100
0-300
0-600
0-900
0-250
0-500
0-750
0-125
0-250
0-500
0-100
0-200
0-60
0-125
0-250
0-200
0-30
0-60
0-100
Voltage @ Full Load
35mV
30mV
30mV
35mV
35mV
35mV
20mV
20mV
20mV
15mV
15mV
15mV
15mV
15mV
18mV
25mV
25mV
40mV
HeightRMSCurrent (A)Voltage (V)
7"
8.75"
12.25"
7"
8.75"
12.25"
7"
8.75"
12.75"
7"
8.75"
7"
8.75"
12.25"
12.25"
7"
8.75"
12.25"
MODEL TCRPANELOUTPUT RIPPLE
7.5T300
6T600
6T900
10T250
10T500
10T750
20T125
20T250
20T500
30T100
30T200
40T60
40T125
40T250
50T200
80T30
80T60
100T100
0-120
0-120
0-160
0-160
0-160
0-250
0-250
0-250
0-500
0-500
0-500
The TCR units have a panel width of 19 inches and a depth of 22 inches.
0-20
0-40
0-15
0-30
0-60
0-10
0-20
0-40
0-5
0-10
0-20
40mV
40mV
60mV
60mV
60mV
90mV
90mV
90mV
125mV
125mV
125mV
TABLE 1
7"
8.75"
7"
8.75"
12.75"
7"
8.75"
12.85"
7"
8.75"
12.25"
120T20
120T40
160T15
160T30
160T60
250T10
250T20
250T40
500T5
500T10
500T20
II INSTALLATION
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83-467-001 Rev. A
II.1 INITIAL INSPECTION
Before shipment, this instrument was inspected and found to be free of mechanical
and electrical defects. As soon as the unit is unpacked, inspect for any damage that
may have occurred in transit. Check for broken knobs or connectors, that the
external surface is not scratched or dented, meter faces are not damaged and that
all controls move freely. Any external damage may be an indication of internal
problems.
NOTE: If any damage is found, follow the "Claim for Damage in Shipment:
instruction in the warranty section of this manual.
II.2 POWER REQUIREMENTS
This power supply requires a three-phase input, of the specified voltage and
frequency, with nominal voltage line-to-line (three-wire system).
Phase rotation need not be observed when connecting power line to the input
terminals of the power supply. No neutral connection is required, but for safety, the
chassis ground terminal marked GRD must be connected to earth ground in
accordance with electrical code requirements.
All AC input connections are made at the rear terminal block, TB2, with the insulated
rectangular covering. Install the three-phase line to terminals marked ØA, ØB and
ØC. Connect the ground line to terminal marked GRD. Reinstall cover plate. The
user should ensure that the AC input wires are of the proper gauge. For example,
the line current is 50 ampere (maximum) for a 230 VAC input, dictating that each
conductor be at least number 8 gauge wire. The safety ground wire must be the
same gauge as the AC input wires to ensure that it does not open and create a
safety hazard. Load wires to be connected to the POS and NEG output terminals
must be heavy enough leads to prevent substantial IR drops between the output
terminals and the load. Remote sensing can be used to compensate for IR drops.
Reference Section 3.3.2.
II.3 LOCATION
This instrument is fan cooled. Sufficient space must be allotted so that a free flow of
cooling air can reach the sides of the instrument when it is in operation. It must be
used in an area where the ambient temperature does not exceed 40° C.
Page 6 of 29
83-467-001 Rev. A
III OPERATING INSTRUCTIONS
1
POWER
PHASE LOSS
TCR POWER SUPPLY
4 5
VOLTAGE CURRENT
O.V.
ADJUST
7
8
2
FIGURE A: FRONT PANEL CONTROLS AND INDICATORS
III.1 TURN-ON CHECK OUT PROCEDURE
1) The front panel surface contains all the controls and indicators necessary to
operate the supply in its normal mode. The following checkout procedure
describes the use of the front panel controls and indicators (Figure A) and
ensures that the supply is operational. This preliminary check of the supply is
done without a load connected.
2) Check the barrier jumper straps on the back of the unit, as shown in Figure 1,
showing TB2 strip-normal operation.
3) Set all controls completely counterclockwise.
4) Turn the CIRCUIT BREAKER (1) on/off switch to "on". The fans will start
immediately but there is a 10 to 15 seconds delay before voltage or current
output will occur. This is caused by the soft start circuit.
9
3 6
Rev.A
Page 7 of 29
83-467-001 Rev. A
5) The PHASE LOSS INDICATOR (2) should be off.
6) Advance CURRENT CONTROL (6) one-half turn and slowly advance VOLTAGE
CONTROL (3). The DC VOLTMETER (4) will deflect from zero to maximum
rating of the supply as this control is advanced completely clockwise. The
VOLTAGE INDICATOR (5) will be lit.
7) Return all controls completely counter-clockwise.
8) To check out constant current, first turn-off supply. Connect a shorting bar
across the plus and minus output terminal at the back of the unit.
9) Turn the circuit breaker-on/off switch to "on". Advance the VOLTAGE
CONTROL (3) one turn clockwise and slowly advance the CURRENT
CONTROL (6). The DC AMMETER (7) will deflect smoothly from zero to the
rated current of the supply as this control is advanced clockwise. The
CURRENT INDICATOR (8) will be lit.
10) Return all controls completely counter-clockwise and turn unit off. Disconnect
output shorting bar.
III.1.1 oVP operation - figure a
If supply is equipped with an overvoltage crowbar, the front panel will contain
OVERVOLTAGE ADJUSTMENT (9). This potentiometer may be adjusted through
an access hole in the front panel.
NOTE: All overvoltage circuitry has been properly adjusted to their respective unit
before leaving the factory.
For trip levels less than the maximum output voltage or to check the overvoltage
circuitry, simply set the potentiometer (9) fully clockwise. Now adjust the power
supply output voltage to the desired trip level (3) and slowly adjust the potentiometer
(9) counterclockwise until OVP trips turning off the set.
Once fired, the SCR remains on until its anode voltage is removed (decreased below
its "on" level) or until anode current falls below a minimum "holding" current. A power
supply that has been thrown into "crowbar" must have its input power momentarily
removed to extinguish the "on" SCRs. Turning the unit off and then on again will
reset the OVP provided the output is not adjusted above the trip point. The
overvoltage range is from 50% to 100% of the maximum output voltage of the unit.
If any of the above events do not occur, the supply is defective and must not be
operated. Depending on circumstances, either warranty service or troubleshooting
as described elsewhere in this manual is required.
Page 8 of 29
83-467-001 Rev. A
III.2 GENERAL OPERATION
The voltage and current controls (local and remote) set the boundary limits for the
output voltage and current respectively. The relationship of load resistance to
control settings determines whether the power supply is operating in constant
voltage or constant current mode. Automatic crossover between modes occurs at
the following load resistance value:
LoadResis tance (Ohms) =
At higher load resistance, the power supply operates in the constant-voltage mode
and at lower resistance in the constant-current mode.
III.3 MODES OF OPERATION
This power supply is designed so that its mode of operation is selected by making
strapping connections between terminals on terminal strip, TB2, which is bolted to
the rear panel of the power supply. The terminal designations are silk-screened on
the rear panel of the power supply. Refer to the following chart.
6
Voltage Control Setting (Volts)
Current Control Setting (Amps)
PIN DESCRIPTIONTB2 - PIN
+ Voltage (+V)1
+ Voltage Remote (+V REM)2
Voltage Programming Current (V PROG I)3
Voltage Amplifier (V AMP IN)4
Voltage Programming Resistive (V PROG R)5
Voltage Programming Resistive Common (V
PROG R COM)
III.3.1 normal operation (Figure 1)
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83-467-001 Rev. A
- Voltage Remote (-V REM)7
- Voltage (-V)8
Current Programming Current (I PROG I)9
Current Amplifier (I AMP IN)10
Current Programming Resistive (I PROG R)11
- Shunt (-I)12
Inverted Amplifier (INV AMP IN)13
+ Shunt (+I)14
Pins 15 and 16 Remote Voltage Turn-On15
(Remote V IN)16
Pins 16 and 17 Remote Dry Contact Turn-On16
(Remote SW)17
When shipped from the factory, each supply is configured for constant/voltage,
constant/current, local programming, local sensing, and single unit mode of
operation. This normal mode of operation is usually used in most applications. All
performance specifications unless otherwise stated are defined in this configuration.
Ripple, programming speed, transient response and stability are optimized with the
supply so configured.
1 2
A. WITH DRY CONTACT 16-17
B. REMOTE ON/OFF AC/DC
3
4 5 6 7 8 9
10 11 12
13 14 15
16 17
171615
+
FIGURE 1: NORMAL OPERATION
Connecting Load
Each load must be connected to the power supply output terminals using separate
pairs of connecting wires. This will minimize mutual coupling effects between loads
and will retain full advantage of the low output impedance of the power supply. Each
pair of connecting wires must be as short as possible and twisted or shielded if
strong AC or RF fields are present to reduce noise pickup. (If a shielded pair is used,
connect one end of the shield to ground at the power supply and leave the other end
disconnected).
A
TB2
B
III.3.2 remote sensing (figure 2)
In applications where the effect of the voltage drop (IR) of the DC load wires would
adversely affect the performance of the load it is possible to sense the voltage at the
load instead of the output terminals of the power supply. Remote sensing will
therefore remove the effect of changes in load current through the power distribution
system. The maximum available load voltage then equals the rated power supply
output voltage less the total of the IR drop.
Connections for Remote Sensing
1) Remove jumpers between the following terminals:
TB2-1 and 2
TB2-7 and 8
2) Connect the positive point of load to TB2-2.
3) Connect the negative side of the load to TB2-7 and 6.
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83-467-001 Rev. A
4) If the sense points are separated from each other by some distance, it is
sometimes necessary to connect a capacitor across the load or between TB2-2 and
TB2-7 within the range of .5 to 50µf.
NOTE: Since the voltmeter is internally connected to the sensing terminals, it will
automatically indicate the voltage at the load, not the power supply output terminal
voltage.
1 2
TB2
3
4 5 6 7 8 9
10 11 12
13 14 15
16 17
+
TWISTED PAIR
LOAD
FIGURE 2: REMOTE SENSING
III.3.3 remote programming
This power supply may be operated in a remotely programmed mode (externally
controlled) by the use of an external resistance. The wires connecting the
programming terminals of the supply to the remote programming device should be
twisted or if strong AC or RF fields are present, shielded.
CAUTION: If the remote programming function fails or is inadvertently adjusted so
that the output voltage is programmed to levels of greater than 15% above ratings,
damage to the output filter capacitors may occur. To protect against this, it is
suggested that the overvoltage protection option be used to limit the maximum
voltage excursion and safely shut the power supply down.
Page 11 of 29
83-467-001 Rev. A
III.3.4 remote programming by external resistance (figure 3 & 4)
FIGURE 4: REMOTE PROGRAMMING BY EXTERNAL RESISTANCE, CURRENT MODE
Voltage Channel
TB2
1 2
3
4 5 6 7 8 9
10 11 12
13 14 15
16 17
5K
FIGURE 3: REMOTE PROGRAMMING BY EXTERNAL RESISTANCE, VOLTAGE MODE
A resistance of 0 to 5000 Ohms programs the output from zero to full rated voltage.
Prog (Ohms) = 5000 X Desired Voltage/Full Rated Output Voltage
1) Remove the jumper between terminals TB2-4 and 5.
2) Connect the programming resistance between terminals TB2-3 & 4 and TB2-7.
Current Channel
A resistance of 0 to 100 Ohms programs the output from zero to full rated current.
Prog (Ohms) = 100 X Desired Current/Full Rated Current
1) Remove the jumper between terminals TB2-10 and 11.
2) Connect the programming resistance between terminals TB2-10 and 12.
TB2
1 2
3
4 5 6 7 8 9
10 11 12
100 OHMS
13 14 15
16 17
CAUTION: An opening in the remote programming circuit is effectively a high
programming resistance and will cause an uncontrolled voltage or current rise to the
maximum output of the power supply. This may cause possible damage to the power
supply and/or the load. For this reason, any programming resistor switch must have
shorting contacts. This type of shorting switch connects each successive position
before disconnecting the preceding one.
III.3.5 remote programming by external voltage (figures 5 & 6)
Page 12 of 29
83-467-001 Rev. A
The front panel voltage or current control is disabled in this operating mode.
FIGURE 5: REMOTE PROGRAMMING BY EXTERNAL VOLTAGE, VOLTAGE MODE
Voltage Channel
A voltage of 0 to 5V programs the output from zero to full rated voltage.
1) Remove the jumpers between terminals TB2-3, 4 and 5.
2) Connect the programming voltage source between TB2-4 (pos) and TB2-6 (neg).
1 2
3
4 5 6 7 8 9
0-5V
10 11 12
13 14 15
16 17TB2
+
Current Channel
A voltage of 0 to 100 mV programs the output from zero to full rated current.
NOTE: A signal from a higher potential source may be attenuated to this
100mV level by a resistor divider. For best performance, the source
impedance of this divider must not exceed 100 Ohms.
1) Remove the jumpers between terminals TB2-9, 10 and 11.
2) Connect the programming voltage source between terminal TB2-10 (pos)
and TB2-12 (neg).
TB2
1 2
3
4 5 6 7 8 9
10 11 12
13 14 15
16 17
+
0-100MV
FIGURE 6: REMOTE PROGRAMMING BY EXTERNAL VOLTAGE, CURRENT MODE
Page 13 of 29
83-467-001 Rev. A
III.3.6 Remote programming by external current (figures 7 & 8)
The front panel voltage or current control is not disabled in this programming mode.
The front panel control must be left in the clockwise position to maintain the
programming constant or signal to the output.
A current of 0-1mA programs the output from zero voltage to full rated voltage or
current.
Voltage
1) Remove the jumpers between terminals TB2-3 and 4.
2) Connect the programming current source between terminals TB2-4 (pos) and
TB2-6 (neg).
TB2
1 2
3
4 5 6 7 8 9
10 11 12
13 14 15
16 17
+
0-1MA
FIGURE 7: REMOTE PROGRAMMING BY EXTERNAL CURRENT, VOLTAGE MODE
Current
1) Remove the jumper between terminals TB2-9 and 10.
2) Connect the programming current source between TB2-10 (pos) and TB2-12
(neg).
TB2
1 2
3
4 5 6 7 8 9
10 11 12
13 14 15
16 17
+
0-1MA
FIGURE 8: REMOTE PROGRAMMING BY EXTERNAL CURRENT, CURRENT MODE
III.3.7 parallel operation (figure 9)
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83-467-001 Rev. A
NOTE: It is not recommended to operate more than three TCR power supplies in
parallel without thorough evaluation by the user with counseling from the Engineering
Department of Electronic Measurements, Inc.. This will help avoid any failures in the
application because of instability of the power supplies.
The simplest parallel connection is that of attaching the positive and negative
terminals to their respective load points. The procedure is as follows:
1) Turn on all units (open circuit) and adjust to appropriate output voltage.
2) Turn supplies off and connect all positive output terminals to the positive side of
the load and all negative output terminals to the negative side of the load.
NOTE: Individual leads connecting unit to the load must be of equal lengths and
oversized to provide as low an impedance as practical for the high peak currents.
3) Set the current controls clockwise.
4) Turn units on one at a time, until the sum of the power supply current capabilities
exceed the load current drawn.
5) Using the voltage controls balance each unit voltage for equal output current.
Balance the current of each unit for equality.
6) Set the current controls to limit just above running current so that if a unit's output
voltage drifts upward, it will become current limited rather than carry an excessive
share of load current.
IMPORTANT: When the units contain the overvoltage option do not connect them in
parallel without consulting the Engineering Staff of Electronic Measurements.
Irreparable damage will occur if one of the paralleled units goes into overvoltage
without proper paralleling of the OVP option.
+
A
M
D
D
+
C
B
E
S
RAB = RCB
RDE = RFE
F
Page 15 of 29
83-467-001 Rev. A
FIGURE 9: MASTER/SLAVE POWER CONNECTION
FIGURE 10: PARALLEL OPERATION MASTER/SLAVE
III.3.8 PARALLEL OPERATION-MASTER/SLAVE
In this configuration, the power supply designated the master is used to control the
voltage and current operation of all other supplies, referred to as slaves.
1) Disconnect the following jumpers of all slaves:
TB2-13 and 14
TB2-9, 10 and 11
2) Connect a jumper between TB2-10 and 12 of all slaves.
3) Connect a wire between the master supply TB2-12 and TB2-13 of each slave.
4) See Figure 9 for + and - power connections.
5) Set the voltage control of each slave fully clockwise.
6) Turn each slave on and then the master.
7) Adjust the master for required output voltage or current. The output leads from
each power supply must be of equal resistance to a point of load near the supply to
assure equal sharing.
MASTER
TB2
TB2
III.3.9 series operation
Two TCR power supplies can be operated in series simply by connecting the
negative output terminal of one unit to the positive output terminal of the other. The
adjustment of each unit functions independently and the total output voltage is the
1 2
1 2
3
4 5 6 7 8 9
3
4 5 6 7 8 9
10 11 12
10 11 12
13 14 15
13 14 15
16 17
SLAVE
16 17
83-467-001 Rev. A
Page 16 of 29
sum of each unit output voltage. NOTE: The voltage at any output terminal must
never exceed 600V with respect to chassis ground.
SEE: Application note for series master/slave operation. Consult Electronic
Measurements, Inc. Engineering Departments for series operation of more than two
supplies.
III.3.10 remote meters
A remote voltmeter may be connected between terminals TB2-2 (pos) and TB2-7
(neg). If remote sensing is also being used, the remote voltmeter will indicate the
voltage at the load. To indicate the voltage at the power supply output terminals
connect the remote voltmeter between terminals TB2-1 (pos) and TB2-8 (neg).
A remote millivoltmeter, calibrated in amperes, may be connected between terminals
TB2-12 (neg) and TB2-14 (pos). A voltage of 0 to 100mV across these terminals
indicates output current from zero to full rating unless otherwise specified (see main
schematic). To compensate for voltage drops in long remote ammeter leads a meter
movement having a full-scale sensitivity of the less than 100mV is used in series with
a calibrating resistor.
The leads to the remote meters should be twisted, and if strong AC or RF fields are
present, the leads should be shielded. One end of the shield should be grounded to
terminal TB2-14 and other end left floating.
III.3.11 remote turn-on
External Voltage Source
Remove link from TB2-16 and TB2-17. Connect a DC source of 12-24V to terminal
TB2-15 positive and TB2-16 negative.
When AC is used 24-115 volts on terminals TB2-15 and TB2-16 the unit is no longer
polarity sensitive.
Dry Contact
Connect a switch or contactor between terminals TB2-16 and TB2-17. Contact
closed-unit will be on.
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83-467-001 Rev. A
Figure 11
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83-467-001 Rev. A
IV THEORY OF OPERATION
IV.1 GENERAL
The TCR 3 Phase power supply has an SCR module connected in each phase.
These modules work in conjunction with the firing circuit and a feedback loop which
is the constant voltage/constant current "ored" circuit. The feedback loop
determines the firing angle of the SCRs ensuring a regulated AC input voltage is
applied to the primary of the power transformer. This regulated AC voltage is then
adjusted to the proper level by the power transformer. After being full-wave rectified
and filtered a constant output voltage or current is produced.
IV.2 POWER FLOW
This section discusses the basic theory of power and signal flow of the TCR
three-phase power supply. If used as a supplement to the maintenance data
provided in Section V, it will aid in isolation of unit faults. Refer to Figure 11, block
diagram of power and signal flow plus schematics #01-467-001, #01-119-000 and
#01-120-000 when reading this section.
Explanation of power flow is as follows: At turn-on, a three-phase AC input passes
through the RFI filter, circuit breaker CB1, to the SCR module networks.
The SCR modules contain two SCRs per module, which are connected in reverse
parallel. Each SCR conducts upon the simultaneous application of a negative
voltage to its cathode (input AC) and a positive voltage to its gate lead. During the
positive half cycle Q2, Q4 and Q6 is conducting and during the negative half cycle
Q1, Q3 and Q5 will conduct. The gate signal must be from 1-3 volts for the SCR to
fire.
The firing angle of the SCR determines the amount of AC power applied to the input
transformer. Thus the amplitude of the DC output of an SCR that is fired at an early
point of the input cycle provides a higher output than one that is fired later in the
input cycle.
Because of the ease with which SCRs are fired by narrow pulses, the gate-cathode
terminals are paralleled by "low" impedance snubber networks (R7 and C7) to
integrate out narrow noise spikes.
The SCRs operating in conjunction with the firing circuits, controls the amount of AC
power applied to the primary of power transformer T1. This transformer converts the
input AC voltage to the appropriate AC level for the load voltage and current. The
voltage is converted to DC by center-tapped rectifiers CR1 through CR6. (Some
units have bridge type rectifiers). At a high continuous load current, L1 and L2
averages the DC voltage waveform at the input of the filter. At low load current the
inductance is ineffective and capacitors C16 and C17 changes to peak pulse
amplitude for necessary filtering. The phase delay of the input waveform ranges
from approximately 60 degrees at the full rated output to nearly 180 degrees at low
output voltage and current.
Resistor R10 acts as a pre-load to assure stability when the load is disconnected
from the power supply. R11 is connected to the unregulated -15V supply which
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83-467-001 Rev. A
insures that 50-100mA always flows through R10. Without R11 and when the output
voltage is low, little or no current would be flowing through R10 so the output
capacitors would never discharge to zero. CR13 bypasses the current through R10
when the current through R10 exceeds the current through R11.
The bias transformers T2 through T4 have two secondary windings. Terminals 4
and 6 on each transformer produces 50V RMS with respect to the center tap,
terminal 5. This provides two sine wave signals spaced 180 degrees out of phase
for referencing the SCR firing circuit to the line frequency. A voltage of 20V RMS is
produced between terminals 7 and 8 of each transformer. Their voltages are full
wave rectified on the A100 Control Board to provide + and - 15 VDC for control
circuitry.
IV.3 SIGNAL FLOW
All the controlling circuitry for regulation of this supply is located on the A100 Control
Board schematic #01-119-000. Explanation of signal flow is as follows:
The 18-20 volts AC from bias transformers T2 through T4 provides a three-phase
input to the bias section of the A100 Control Board. These inputs are used for
different facets of the controlling process of the power supply. Most of the circuitry
uses the + and - 15 VDC regulated by IC101 and IC102. IC101 produces a +15
VDC with a 150 mA load and IC102 a - 15VDC with a 30mA load. The unregulated
DC voltage is used for voltage with the remote turn-on when dry contact control is
used.
When one of the input phases drops out, the conduction cycle of Q108 is reduced,
allowing capacitor C129 to start charging. After three cycles of line frequency, C129
charges sufficiently to cause Q109 to conduct which turns on the front panel phase
loss LED. This effectively grounds the drive circuit preventing the generation of
further SCR gate pulses which shuts down the output of the unit.
The AC dropout circuit prevents the power supply from operating when the AC drops
below operating range. This circuit works as follows: C128 will start discharging
through R149. This will cause Q107 to start conducting grounding the firing line to
the SCRs and resets the "soft start" circuit.
Once input power is at the operating level, the "soft start" circuit will reset in the
following manner: Capacitor C134 slowly starts charging through the base of Q110.
As C134 charges, the base current will decrease allowing the collector voltage of
Q110 to slowly rise which gradually increases the conduction angle of the SCRs.
Separate constant current references are provided for the voltage and current
channels. The collector current of Q111 drives the voltage channel and Q112 the
current channel. These current sources are referenced by the voltage across
CR133, a temperature-compensated zener diode. Since the voltage difference
across the summing junction of IC104 Pin 2 is essentially zero, the voltage across
CR133 also appears across the series combination of R167 and R168 (also R171
and R173) since the Vbe of Q111 and Q112 is essentially equal. A constant voltage
across a fixed resistance produces a constant current. A constant emitter current
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83-467-001 Rev. A
produces an essentially constant collector current. The current from each of these
sources is adjustable to 1mA by R167 and R171.
The reference current level for the voltage channel flows from J107-2 to TB2-3.
With jumpers between terminals TB2-3, 4 and 5, the voltage level produced when
this current flows through the voltage control R16 is applied through J107 Pin 10 of
IC104. The signal on the other input of IC104 Pin 9 is derived from the power supply
output voltage level through voltage divider R177 plus R178 and R179. Maximum
rated output voltage produces +5 VDC at Pin 9 of IC104. With R16 in the fully
clockwise position, +5 VDC is applied to Pin 8 of IC104. If the attenuated output
voltage changes from the value set by R16 (because of load changes, for example)
an error signal will be developed at the output of IC104, Pin 10. This error signal, via
the SCR control circuitry, will cause a proportional change in the output voltage so
as to bring the voltage on Pin 9 of IC104 equal to that applied to Pin 8.
The action of the current channel is identical to that of the voltage channel with the
exception that the controlled quantity is being sampled across the shunt R12. This
sampled voltage is compared to the reference voltage produced at Pin 6 of IC104,
which is established from the front panel current control R17. (0 to 100 mV for all
units except 600 and 900 amps, which are 0 to 50 mV).
The output of the voltage channel amplifier and the current channel amplifier are
"ored" together by diodes CR136 and CR139. Whichever channel has a higher
positive output signal over-rides the effect of the other and becomes the channel
controlling the DC output. The output of either the voltage or current channel is fed
to the base of transistor Q110 which operates as a linear amplifier whose output is
fed to the phase control circuit Q101-106.
The mode indicator lights are controlled by the outputs of the voltage and current
channels. For example, if the voltage channel is in control, output of the current
channel is negative. This will cause current to flow through CR135 lighting the
voltage LED. When the current channel is in control, current will flow through
CR134 lighting the current LED.
The voltage signal developed across R164 is a source of feedback fed through
R187 and C145, and R182 and C142, to stabilize the current and voltage channels
respectively. Additional loop compensation is provided by R183 and C143, and
R185 and C144.
A control signal that momentarily switches negative at the base of Q110 allows the
collector ramp voltage to increase the firing line voltage earlier in the cycle thus
increasing the SCR firing angle. A positive-going signal at the cathodes of CR136
and CR139 causes the output of the power supply to reduce by retarding the
conduction of the SCRs. This shows that the amplitude of the phase angle is directly
proportional to the polarity of the base signal of Q110. The collector voltage of Q110
is approximately 7 to 8 volts at full conduction angle and 5 to 6 volts for minimum
conduction angle.
IV.4 SCR FIRING CIRCUIT
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83-467-001 Rev. A
The SCR firing pulses are developed by properly timed conduction of Q1 thru Q6.
This is accomplished by the combination of the phase related AC signals from
terminals 4, 5 and 6 of T2, T3 and T4 and the variable level from Q110.
Examining the typical firing circuit for one SCR only, R101 and CR101 produce a
12V square wave at line frequency with axis crossings at 0° and 180°. R107 and
C102 integrate the square wave into rising and falling ramp voltages with transition
in voltage direction occurring just past 0° and 180° due to the phase shifting effect of
the RC network. When a positive DC level from Q110 via J7-15 is superimposed on
the ramp voltage across C102, Q101 will be driven into conduction at some time
during the positive-going position of the ramp. This conduction causes a sudden
current flow in the primary of T101 and a resultant pulse of trigger current from the
secondary winding of T101 to the gate of SCR Q1. Operation of the opposite firing
circuit is identical except for 180° displacement of the gate pulse which fires Q2
when its anode is positive.
C109 through C114 store the SCR gate pulse energy, and C108 and R128 serve as
a filter to prevent pulse loading of the +15V supply. Resistors designated "*3" on the
A100 schematic are selected at test to equalize SCR firing angles.
Thermal switch TS1 is connected across C134. If the diode heatsink temperature
rises excessively, the thermal switch closes causing Q110 to be driven into
saturation, thus shutting down the power supply output. The thermal switch will
reset automatically when the heatsink temperature drops sufficiently.
IV.5 REMOTE TURN-ON
Remote Turn-On allows the user to turn the supply on from a remote location with
12-24 VDC or 24-115 VAC or a dry contact closure. IC103 isolates the remote
turn-on circuitry from the power supply common.
Transistor Q110 is held in saturation by the 15 volts of the bias supply through R157
and CR130. When the internal LED of IC103 is activated by power at Pins 1 and 2,
the internal darlington transistor causes most of the 15 volts to be shunted to
ground. This allows Q110 to start amplifying.
When a N/O voltage switch (dry contact) for remote turn-on is used, Q113, L101,
and CR129 supply the control signal for the optical isolator. Q113 is connected
across the unregulated 20 DC volts of the bias supply and is used as a relaxation
oscillator.
Each time Q113 conducts, it discharges C147 through L101 inducing a voltage in its
secondary winding. This voltage is rectified by CR129 and filtered by C156. When a
switch is connected between J12-3 and J12-2 the voltage will make a complete loop
to operate the optical isolator.
IV.6 OVERVOLTAGE PROTECTION OPTION (A200 PCB #01-120-000)
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83-467-001 Rev. A
The OVP option protects the power supply and the load from excessive output
voltage caused by a failure in the control circuitry of the power supply, or a defect or
misadjustment in the remote control circuit. IC201, Pin 2 samples the power supply
output voltage level through voltage divider R202, R203 and R204. Capacitor C204
connected to Pins 3 and 4 determines the minimum duration of the overvoltage
condition before the OVP trips. When the input voltage rises above the trip point set
by an internal reference source, capacitor C204 begins charging. When the voltage
at Pins 3 and 4 goes above the minimum duration output of IC201 Pin 8 goes
positive and turns on Q201, Q202 and Q203.
SCR Q201 is connected to the collector of Q110. When Q201 conducts it shorts the
firing line inhibiting the input SCRs. On low voltage power supplies, the voltage
available is not high enough to trip the circuit breaker, therefore, the charged energy
from a +15V capacitor, C206 is used to trip the breaker. On power supplies above
10 volts C206 and CR206 are not used. Q202 applies the DC output voltage to the
circuit breaker.
Q203 and R211 serve as a low impedance high current short to crowbar the output
to zero. This will prevent voltage damaging overshoot which could occur with a
shorted SCR.
IV.7 DIGITAL METER A100 PCB
The major component of the Digital Meter Printed Circuit Board (A100) is a 3 1/2
digital analog to digital converter (IC17136). All necessary active devices are
contained within including seven-segment decoders, display drivers, reference and
clock. It also interfaces with a liquid crystal display and provides the backplane drive
voltage.
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83-467-001 Rev. A
V MAINTENANCE
V.1 GENERAL
A regular scheduled preventive maintenance program is recommended for the TCR
3 Phase power supply. As a minimum, maintenance should consist of a thorough
cleaning of interior and a visual inspection of components on printed circuit boards.
Even a relatively clean location requires at least one inspection every six months.
V.2 INSPECTION AND CLEANING
CAUTION: Always unplug power supply from AC line before removing cover.
1) Remove six 8-32 machine screws from both sides of top cover. Loosen two 8-32
machine screws at top of back of unit.
2) Cover can now be removed.
3) Check for loose wires, burn marks, etc.
4) A100 control board will snap out so it can be checked.
5) Remove dust from in and around parts with a small long bristled brush or
compressed air.
V.2.1 equipment required for calibration and maintenance
1) Oscilloscope - Dual Trace - 20kHz bandwidth - isolated from ground (Tektronix
2213 with 10x voltage probe).
2) RMS Multimeter - 100 VDC - 1000 VAC (Hewlett Packard HP-3465A).
3) VOM (Simpson 260).
4) Load - equal to the output capability of unit.
V.3 CALIBRATION
This procedure applies to the adjustment and calibration of a properly functioning
unit only. Any malfunctions must be corrected before proceeding with calibration. It
is only necessary to remove top cover to make these calibrations. (See Section 5.2)
NOTE: If an external shunt is being used, connect it in series with the short.
1) Connect a voltmeter across the plus and minus sense leads of the shunt capable
of the shunt voltage. The internal shunt of the unit is either 50 or 100 mV.
2) Turn CURRENT and VOLTAGE control completely clockwise.
3) Turn power supply ON.
4) Adjust the ICAL control R171 until the current rating of the unit is achieved.
Page 24 of 29
83-467-001 Rev. A
V.3.1 ammeter calibration
1) Connect the reference ammeter (with shunt as applicable) in series with a load
or short circuit across the output terminals.
2) Turn the VOLTAGE control fully clockwise.
3) Check the zero adjustment of the front panel ammeter.
4) Turn the power supply on.
5) Adjust the CURRENT control so that the reference ammeter indicates full rated
output current of the power supply.
6) Adjust R14 (located just behind the front panel) until the front panel ammeter
reading equals that of the reference ammeter. (Analog meters)
V.3.2 firing balance
1) Connect a load to the unit.
2) Connect oscilloscope probe (x10) on TB2-1 and ground on TB2-8.
3) Adjust R120, R123, R126 for even peak voltages from cycle to cycle of the DC
output.
V.4 TROUBLESHOOTING
The power supply is divided into two basic circuit areas, power flow and signal
control. The power flow circuitry consists of circuit breaker, SCRs, power
transformer, rectifiers, choke and capacitors as well as the cabling interconnecting
them. The signal control circuitry is contained on the removable printed circuit card.
Most unit malfunctions will originate on the circuit card. Reviewing the Theory of
Operation is recommended before starting to troubleshoot the supply.
WARNING: When servicing supply dangerous voltage levels exist. Be especially
careful of personnel and equipment when measuring primary circuitry since this is at
line potential.
V.4.1 overall troubleshooting procedure
1) Check for obvious troubles such as input power failure, loose or incorrect
strapping on rear terminals of defective meter.
2) It is common for the trouble to be caused by the DC bias or reference voltages,
thus it is a good practice to check voltages on the A100 control board before
proceeding to the next step. The A100 board may be disconnected from the SCRs
by pulling plugs J1-J6.
Some voltages to check with respect to negative terminal on standard units are:
Page 25 of 29
83-467-001 Rev. A
+15 volts ± .5VIC101 - Pin 3
2. Disconnect A100 board from
-15 volts ± .5VIC102 - Pin 3
2-3 voltsIC103 - Pin 5
+15 volts ± .5VIC104 - Pin 11
3-8 volts*Q110 - Collector
*This voltage is clamped at 10 volts by CR132.
3) Disconnect load and proceed to the next step.
4) Troubleshooting is more effective if the unit is operated in the normal mode
(Normal Programming, Section 3.3.1).
5) Before turning on the supply turn both CURRENT and VOLTAGE channel
controls completely off (counterclockwise).
Where only one terminal is specified measurements are made with respect to I shunt
common or a negative output terminal.
The chart that follows is a troubleshooting guide that should aid in discovering
operational problems in the supply.
V.4.2 TROUBLESHOOTING CHART
Turn Supply On
PROBLEMSTART
Output goes high - Full scale or above. If unit
contains OVP option - Circuit breaker trips.
1. Turn set off.
SCRs pulling plugs J1-J6.
3. Turn set on.
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83-467-001 Rev. A
the voltage across it will vary from zero
REMEDYPROBLEM
SHORTED SCR.SET STILL OUT OF CONTROL
CHECK R16 AND R17 - COULD BE OPEN.SET NO LONGER OUT OF CONTROL
Check R16
1. Connect digital-meter to J7-2 and
common.
2. As R16 is rotated through its ranges,
to 3-5 volts.
Check R17
1. Connect digital-meter to J7-9 and
common.
2. As R17 is rotated through its range the
voltage across it will vary from 0-50 or
0-100mV depending on the unit.
Check transistor Q110 on the A100 control
board, could be open.
PHASE LED LIT.UNIT ON BUT NO OUTPUT
Check AC input voltage.
CHANNELS UP SLOWLY
Check AC signal at J113-2, 3 and 4 on A100
Control Board.
Check output of bias transformer T2, T3 and
T4 across Pins 7 and 8. Open circuit voltage
20 volts AC.
If there is not voltage at the bias transformers
check, fuses F1-3.
PHASE LED NOT LIT
Check transistor Q110 on the A100 Control
Board, could be shorted.
Check transistors Q107 and Q109 on the
A100 Control Board, could be shorted.
Check transistor Q108 on the A100 Control
Board, could be open.
CIRCUIT BREAKER SNAPS OFFTURN VOLTAGE AND CURRENT
One of the high power diodes located on the
heatsink could be shorted. Refer to Section
5.5 for diode replacement.
Check output filtering capacitors C16 and C17EXCESSIVE RIPPLE
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83-467-001 Rev. A
NOT REGULATE
1. Check for equal ramp amplitudes
V.4.3 overvoltage troubleshooting
Most overvoltage faults fall into two general categories:
1) The circuit overvoltage fires at all times even when the trip point is adjusted to
maximum.
could be defective.
One of the main SCRs (Q1-Q6 could be
open).
Inductor coils L1 or L2 could be shorted.
SCR control circuit on the A100 Control Board
could be defective.
across CR101-106.
2. Check that the waveform across
C109-114 drops rapidly to 1.4 volts.
Check C142 and C145, could be defective.UNIT IS OSCILLATING
Check IC104 and Q110, could be defective.CURRENT OR VOLTAGE CHANNEL DOES
Check SCRs Q201 and Q202. They could be shorted.
IC201 could be defective.
2) The overvoltage is completely inoperative at any trip point setting.
Check SCRs Q201 and Q202. They could be open.
IC201 could be defective.
V.5 PRIMARY DIODE REPLACEMENT
1) The bottom and side cover is all one piece and must be removed to replace
diodes.
2) Remove five 8-32 screws on each side of unit cover.
3) Remove covering.
4) Turn set over to rest on top.
5) Diodes are located on bottom of unit mounted to a heatsink.
6) After removing diodes, wipe heatsink clean of all compound.
7) Put a fine coating of compound (low thermal contact resistance) on surface of
diode that meets heatsink. Be careful not to get any on threads of diode.
8) Mount diodes to heatsink with sheetmetal ("PAL") nut. Torque chart follows:
Page 28 of 29
83-467-001 Rev. A
9) Use a new nut when a new diode is installed.
V.6 FAN REPLACEMENT
After the fan is replaced the voltage across the fan motor should be measured and
compared to the nameplate rating. If the voltage is not correct change the series
resistor (R18, R19, R20, R21, R22, R23).
This addendum covers the difference between the 2.5 - 10kW package and the 15kW.
AC INPUT:
The AC line current will be approximately 60 amps and the front panel circuit breaker is
70 amps.
TORQUE PRESSUREDIODE THREAD SIZE
30 inch pound - max. torque1/4 - 28 threaded device
120 inch pound - max. torque3/8 - 24 threaded device
130 inch pound - max. torque1/2 - 20 threaded device
30 foot pound - max. torque3/4 - 16 threaded device
TCR THREE-PHASE
15kW ADDENDUM
COOLING:
The air flow is from right to left with some air flow out the top and back.
RATING TABLE:
OUTPUT RATINGS
VOLTAGE AT FULL LOAD
HEIGHTRMSCURRENTVOLTAGE
The 15kW schematic is the same as the 10kW package except for (6) fans, TWO connected
between each of the 3 phases. The fans are the same as the ones used on the 10kW unit.
The OVP part number is listed on the schematic #01-467-001. The OVP for this unit should be
bought as a complete assembly, therefore no schematic will be provided.
MODEL TCRPANEL SIZEOUTPUT RIPPLE
4T90017.535mV9004
6T90017.535mV9006
30T50017.520mV50030
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83-467-001 Rev. A
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