The IS200EPSMG2A is an Exciter Power Supply Module designed by General Electric (GE) for its EX2100™ Regulator Control System. This module is the version within the EPSM series specifically dedicated to the EX2100 regulator control. Its primary function is to convert the DC link voltage into various stable voltages required by the regulator control system, providing reliable power to controllers and associated peripheral devices. Unlike the IS200EPSMG1A, the IS200EPSMG2A module has an EPSD daughter board mounted on it to accommodate higher input voltages and meet the specific requirements of regulator control.
The IS200EPSMG2A module utilizes a two-stage topology consisting of a buck-regulator and a push-pull inverter. The input voltage is first converted to a 50 V dc intermediate voltage by the buck-regulator. This intermediate voltage then passes through the push-pull inverter and transformer to generate multiple isolated outputs. The transformer provides high-voltage isolation between the input power source and the control system, ensuring equipment and personnel safety. The EPSD daughter board mounted on the module allows the EPSMG2A to safely handle higher input voltages by increasing creepage and clearance distances. It also provides a fuse before the buck-regulator for input overcurrent protection.
In the EX2100 regulator control system, a simplex system uses one IS200EPSMG2A module installed in the Exciter Regulator Backplane (ERBP). A redundant system uses two IS200EPSMG2A modules: one installed in the ERBP (powering M1) and another installed in the Exciter Regulator Redundant Backplane (ERRB, powering M2/C). Each IS200EPSMG2A delivers power to the backplane via its connectors, which is then distributed to other boards and peripheral devices.
Output voltages of the IS200EPSMG2A module include:
+5 V dc: Powers digital circuits on control boards
±15 V dc: Powers analog circuits
+24 V dc: Powers the control backplane
±24 V dc (P24B/N24B): Powers fans, relays, and the DC feedback board
+70 V dc (Isolated): Provides contact wetting voltage for terminal boards, dynamic discharge board, and redundant relay board
20 V ac (AC17): Powers IGBT gates and the dynamic discharge board
±55 V dc (P55/N55): Powers ground detector circuits on the options card
The module front panel features seven green LED indicators, each indicating the status of an individual output voltage. Multiple fuses inside the module provide overcurrent protection for the output circuits. Additionally, the module provides 13 test points for convenient on-site measurement of output voltages and commons. The IS200EPSMG2A module has no adjustable jumpers; all parameters are set at the factory.
II. Main Functions
The primary functions of the IS200EPSMG2A include, but are not limited to, the following:
1. Input Voltage Conversion
The IS200EPSMG2A receives input voltage from the DC link (via the EPSD daughter board) and converts it into multiple stable voltages required by the regulator control system via internal circuitry.
2. Multiple Isolated Outputs
Through the push-pull inverter and transformer, the IS200EPSMG2A generates multiple mutually isolated output voltages to meet the power requirements of different loads:
+5 V dc: Powers digital circuits on control boards
±15 V dc: Powers analog circuits on control boards
+24 V dc: Powers the control backplane
±24 V dc (P24B/N24B): Powers fans, relays, and the DC feedback board
+70 V dc (Isolated): Provides contact wetting voltage for terminal boards, dynamic discharge board, and redundant relay board
20 V ac (AC17, 25 kHz square wave): Powers IGBT gates and the dynamic discharge board
±55 V dc (P55/N55): Powers ground detector circuits on the options card
3. High-Voltage Input Adaptation
The EPSD daughter board mounted on the IS200EPSMG2A allows the module to safely handle high-voltage input from the DC link by increasing creepage and clearance distances. The daughter board also includes a 600 V, 5 A fuse (FU1) for input overcurrent protection.
4. High-Voltage Isolation
The transformer in the push-pull inverter provides electrical isolation between the high-voltage input side and the low-voltage output side, with isolation levels meeting industrial safety standards, protecting control circuits and personnel.
5. Status Indication
The front panel features seven green LED indicators, each corresponding to an output voltage. When an output voltage is normal, its corresponding LED illuminates, providing intuitive power status indication for operation and maintenance personnel.
6. Overcurrent Protection
Each output circuit is equipped with fuses. In case of a load short circuit or overcurrent, the fuse blows, protecting the module and downstream equipment. Refer to the technical specifications table for specific fuse configurations.
7. Test Points
The module provides 13 test points for conveniently measuring output voltages and commons during commissioning and troubleshooting.
8. Redundant Architecture Support
In redundant regulator control systems, M1 and M2/C each have an independent IS200EPSMG2A module for power supply. If a module fails, it can be replaced after system shutdown (online replacement is not supported).
III. System Applications
1. Application in EX2100 Regulator Control System
The IS200EPSMG2A is the core power module powering controllers and peripheral devices within the EX2100 Regulator Control System. Its roles within the system include:
Controller Power Supply: Provides +5 V, ±15 V, and +24 V operating power for boards in the regulator control system.
IGBT Gate Drive Power Supply: Provides 20 V ac (25 kHz square wave) for IGBT gate drive circuits and the dynamic discharge board.
Contact Wetting: Provides isolated +70 V for contact wetting on terminal boards, dynamic discharge board, and redundant relay board, ensuring reliable contact detection.
Ground Detection Power Supply: Provides ±55 V for ground detector circuits on the options card.
Peripheral Device Power Supply: Provides ±24 V for fans, relays, and the DC feedback board.
2. Typical Application Scenarios
EX2100 regulator control systems for synchronous generators
Power supplies for steam turbine generator voltage regulators
Regulator systems for hydro turbine generators
Regulator systems for gas turbines
Upgrades and retrofits for industrial regulator systems
IV. Detailed Interface Description
1. EPSD Daughter Board and Input Connectors
The IS200EPSMG2A module has the EPSD daughter board mounted for high-voltage input adaptation. Connectors P3/P3D and P4/P4D on the daughter board are used for input power connection:
| Connector | Pins | Signal | Description |
| P3/P3D | 1-8 | M*_PWR_IN_P | Current-limited DC link positive input (to EPSM via EPSD) |
| P4/P4D | 1-8 | M*_PWR_IN_N | DC link negative input to EPSM, PSCOM |
Note: M can be M1 (for ERBP) or M2/C (for ERRB) depending on the installation location.
2. Backplane Connectors P1 and P2
The IS200EPSMG2A module connects to the ERBP or ERRB backplane via two backplane connectors, P1 and P2, delivering the various output voltages to the backplane for distribution to other boards and connectors.
3. Front Panel LED Indicators
Seven green LEDs on the module front panel correspond, from top to bottom, to:
| LED | Corresponding Output Voltage |
| 1 | +5 V |
| 2 | +15 V |
| 3 | -15 V |
| 4 | +24 V A |
| 5 | +24 V B |
| 6 | -24 V B |
| 7 | +70 V |
During normal operation, all LEDs should be steadily lit. If an LED is off, it indicates that the corresponding output voltage is missing, possibly due to module failure or a blown fuse.
4. Fuses
The IS200EPSMG2A module contains multiple fuses internally for overcurrent protection on each output. Additionally, the EPSD daughter board includes an input fuse FU1 (600 V, 5 A). Fuses are located inside the module; replacing the module does not require separate fuse replacement. If a fuse blows, it typically indicates a fault in that circuit; the load should be investigated before replacing the module.
5. Test Points
Thirteen test points are located inside the module; refer to the layout diagram in the document for specific locations. A multimeter can be used to measure voltages between test points and their corresponding commons to verify output status. Test point descriptions are provided in the technical specifications table.
V. Installation and Replacement
1. Mounting Location
The IS200EPSMG2A module inserts into designated slots in the ERBP or ERRB backplane. Simplex regulator systems use one slot in the ERBP. Redundant regulator systems use one slot in the ERBP (powering M1) and one slot in the ERRB (powering M2/C). During installation, ensure the module is inserted into the correct backplane and slot; incorrect insertion may prevent the control system from functioning properly or damage equipment.
2. Replacement Procedure (System De-energized)
Important Note: The IS200EPSMG2A does not support online replacement. Power to the regulator control system must be turned off before replacement, regardless of whether the system is simplex or redundant.
Safety Warnings:
WARNING: To prevent electric shock, follow the complete de-energizing procedures outlined in the Installation and Startup Guide (GEH-6674). Adhere to all local Lock-out/Tag-out practices. Allow time for capacitors to discharge.
CAUTION: To prevent component damage caused by static electricity, treat all modules with static sensitive handling techniques. Wear a wrist grounding strap and store modules in anti-static bags.
Replacement Steps:
Verify Power Off: Ensure the regulator control system containing the EPSMG2A is completely de-energized. Test circuits before opening the control cabinet door.
Remove Old Module:
Loosen the screws at the top and bottom of the faceplate near the ejector tabs (screws are captive).
Unseat the module by raising both ejector tabs.
Gently pull the module straight out of its backplane slot using both hands.
Install New Module:
Align the new module with the correct backplane and slot, and push it in along the guides.
Using thumbs, firmly press the top and bottom of the faceplate simultaneously to initially seat the module.
Alternately tighten the top and bottom faceplate screws evenly to ensure the module is squarely seated.
Restore Power: Restore power to the regulator control system following procedures. Check that all LED indicators on the IS200EPSMG2 module are lit and that the green power LEDs on the corresponding controller boards are also lit.
