GE IS200EXHSG3A Exciter High-Speed Relay Driver Board

The IS200EXHSG3A is an Exciter High-Speed Relay Driver Board designed by General Electric (GE) for its EX2100™ Excitation Control System. This board is the version within the EXHS series specifically dedicated to redundant control systems and used with standard contactors. It primarily provides drivers for the DC contactor (41) and pilot relays for de-excitation and field flashing.

The IS200EXHSG3A board plays a critical interface role in the EX2100 excitation control system, converting logic commands from the control system into relay outputs that drive high-power field devices. It connects to the EMIO board via the EBKP backplane. In redundant control systems, it receives signals from the M1, M2, and C controllers, controlling the relay coils through a 2-out-of-3 voting circuit, ensuring high system reliability.

The IS200EXHSG3A is one of four versions in the EXHS series. According to the table in the document, the main differences between each version are as follows:

The IS200EXHSG3A is designed specifically for redundant control systems, suitable for 500 A, 42 mm bridges, and used with standard contactors featuring 125 V dc coils. Unlike the G1 and G2 versions, the G3 and G4 versions omit the current regulator circuit; the driver provides a constant 125 V voltage to the coil.

The board integrates the following key components:

• K53A and K53B Flashing Pilot Relays: Control the flashing contactors 53A and 53B.

• KDEP De-excitation Pilot Relay: Controls the de-excitation relay.

• K41 Contactor Drivers: Two (K41A, K41B) for controlling the 41 DC contactor.

• Signal Conditioning Circuits: Process de-excitation status signals and Crowbar status signals from the EDEX board.

• Contact Input Circuits: Monitor the status of auxiliary contacts for 41, 53A, and 53B.

  
  

II. Main Functions

The primary functions of the IS200EXHSG3A include, but are not limited to, the following:

1. 41 DC Contactor Drive

The IS200EXHSG3A provides two 41 DC contactor drivers (K41A, K41B), controlled by drivers on the EMIO. The driver on the EMIO requires both a command from the Field Programmable Gate Array (FPGA) and the 86G contact to be closed before energizing the driver. Either the FPGA or the 86G contact can cause the driver to de-energize.

In a redundant control system (G3), inputs from the M1, M2, and C controllers control three relays connected in a 2-out-of-3 voting circuit. The relay coil is powered by 24 V dc from M1 and M2.

Unlike the G1 and G2 versions, the G3 version omits the current regulator circuit. The driver provides a constant 125 V voltage (P125) to the coil, rather than a high-voltage boost followed by a constant current hold mode.

2. Flashing Pilot Relay Control

The IS200EXHSG3A board integrates two flashing pilot relays, K53A and K53B, used to control the field flashing contactors. Each flashing pilot relay is controlled by the EMIO and uses two series contacts to drive one flashing contactor. The relay coil is powered by 24 V dc from the M1 controller.

K53A/K53B Relay Characteristics:

• Contact Power: Nominal 125 V dc (140 V dc max), supplied through J9 from the exciter control.

• Resistive Load: 5 A @ 28 V dc, 0.5 A @ 125 V dc.

• Inductive Load: 2 A @ 28 V dc, 0.2 A @ 125 V dc, L/R time constant 0.007 seconds.

• With Suppression: 0.5 A @ 125 V dc, L/R time constant 0.10 seconds (2 poles in series).

• Suppression: Supplied on the EXHS board.

• Agency: UL, CSA.

3. De-excitation Pilot Relay Control

The IS200EXHSG3A board integrates one de-excitation pilot relay, KDEP, used to control the de-excitation circuit. KDEP becomes active instantly upon the de-activation of the 41 relay. The KDEP coil is connected to a 125 V dc power supply.

KDEP Relay Characteristics:

• Coil Power: Nominal 125 V dc from J9 (140 V dc max, 100 V dc min).

• Contact Power: Nominal 24 V dc from the exciter cabinet.

• Resistive Load: 2 A @ 28 V dc.

• Inductive Load: 1 A @ 28 V dc, L/R time constant 0.007 seconds.

• Suppression: Supplied on the external coil, none on the EXHS board.

• Agency: UL, CSA.

De-excitation status signals originate on the EDEX board, are conditioned on the EXHS, and are sent to EMIO-M1 and EMIO-M2 (for redundant control).

4. Contact Input Monitoring

The IS200EXHSG3A board brings in the auxiliary contacts for 53A, 53B, and 41 for monitoring by the EMIO. In redundant control, the signals are fanned out to the M1, M2, and C controllers. The three contacts are wetted by 70 V dc supplied from the EXHS. Power from plugs J12M1 and J12M2 is resistor isolated and supplied to the contacts. The wetting voltage can vary from 63 to 84 V dc. The resulting signals fan out to M1, M2, and C. The contact input monitoring circuit is located on the EMIO.

5. Crowbar Status Input

Crowbar status signals from two EDEX boards are supplied to EMIO-M1 and EMIO-M2 through the EXHS. The conditioning circuit on the EXHS monitors both inputs from the EDEX boards. If either transitions to low impedance (crowbar conducting), it passes a signal to EMIO in M1.

6. Signal Conditioning Circuits

In redundant control, de-excitation signals from two EDEX boards are supplied to EMIO-M1 and EMIO-M2 through the EXHS. There are two signal conditioning circuits on the EXHS, one for each signal. The EXHS repeats the signal to the EMIO.

III. System Applications

1. Application in EX2100 Excitation Control System

The IS200EXHSG3A is a critical interface board connecting control logic and high-power field equipment within the EX2100 Excitation Control System. Its roles in a redundant control system include:

• 41 Contactor Drive: Receives control commands from the EMIO to drive the 41 DC contactor, enabling switching of the excitation system.

• Flashing Control: Controls the flashing contactors via K53A and K53B pilot relays to provide initial field current during unit startup.

• De-excitation Control: Controls the de-excitation circuit via the KDEP pilot relay to rapidly dissipate generator field energy during shutdown or faults.

• Status Feedback: Provides status feedback from the 41, 53A, and 53B auxiliary contacts to the EMIO for system monitoring.

• De-excitation Status Feedback: Conditions de-excitation status signals from the EDEX and sends them to the EMIO.

• Crowbar Status Feedback: Conditions Crowbar status signals from the EDEX and sends them to the EMIO.

2. Redundant Control System Configuration

In a redundant control system, the IS200EXHSG3A receives signals from the M1, M2, and C controllers. The K41 driver control uses a 2-out-of-3 voting circuit, ensuring that a single controller failure does not cause a misoperation or failure to operate. The flashing relays K53A/K53B are controlled by the EMIO and also offer high reliability in redundant systems.

3. Differences from G1/G2 Versions

The main difference between the IS200EXHSG3A and the G1, G2 versions lies in the drive method for the 41 contactor:

• G1/G2: Used for high-speed contactors (32 V, 1.5 A coil). They employ a drive method that first applies a high-voltage boost (125 V for 150 ms) and then switches to a constant current hold mode (1.5 A ±0.2 A).

• G3/G4: Used for standard contactors (125 V dc coil). They omit the current regulator circuit and directly provide a constant 125 V voltage.

Therefore, when selecting an EXHS board, the version must be chosen based on the type of 41 contactor used in the field.

4. Typical Application Scenarios

• Large Steam Turbine Generator Excitation Systems: For excitation control of 500 A, 42 mm bridges.

• Hydro Turbine Generator Excitation Systems: High-reliability applications requiring redundant control.

• Gas Turbine Excitation Systems: Fast-response excitation control in conjunction with the EX2100.

• Industrial Synchronous Motor Excitation: For high-power industrial drives requiring standard contactors.

  
  

IV. Detailed Interface Description

1. Power Connectors

2. Driver Connector

3. Signal Connector J6

4. Signal Connector J7

5. Signal Connector J8

6. Signal Connector J11

7. Connectors to EMIO J505, J508, J515

These three 25-pin connectors connect to the EMIO boards for M1, M2, and C respectively. J505 (to M1) and J508 (to M2) include full de-excitation and Crowbar signals, while J515 (to C) does not include these signals. Refer to the tables in the document for detailed pin assignments.

V. Installation and Replacement

1. Mounting Location

The IS200EXHSG3A board is typically mounted inside the EX2100 excitation control cabinet, secured to a mounting plate with screws. The board connects to the EBKP backplane via cables, which then communicates with the EMIO.

2. Board Replacement Procedure

Safety Warnings:

• WARNING: To prevent electric shock, turn off power to the excitation system and follow the complete de-energizing procedures outlined in the Installation and Startup Guide (GEH-6631). Adhere to all local Lock-out/Tag-out practices.

• CAUTION: Use high-voltage test equipment to confirm circuits are de-energized before touching them.

• CAUTION: To prevent component damage caused by static electricity, treat all boards with static sensitive handling techniques. Wear a grounding strap and store boards in anti-static bags.

Replacement Steps:

1. Verify Power Off: Ensure the excitation system is completely de-energized.

2. Open Cabinet Door: Open the control cabinet door and test I/O circuits to confirm power is off.

3. Label Cables: Verify all cables are correctly labeled according to the markings on the board for easy reconnection.

4. Disconnect Cables: Carefully disconnect all cables from the EXHS board.

5. Remove Old Board:

• Place a rag or other nonconductive barrier below the board to prevent dropped hardware.

• Remove the screws holding the EXHS board and take out the old board.

6. Inspect New Board: Confirm the new board model is IS200EXHSG3A, matching the original board.

7. Install New Board: Orient the new board in the same position as the removed one, align with mounting holes, and secure with screws.

8. Reconnect Cables: Reconnect all cables as labeled, ensuring connectors are properly seated.

9. Restore Power: Close the cabinet door, restore power to the excitation system following procedures, and test operation.

3. Relay Replacement Procedure

Relays on the EXHS board are socketed and can be replaced individually if needed.

1. Diagnose Fault: Use the Toolbox diagnostic tools to identify and record the faulty relay.

2. Verify Power Off: Ensure the excitation system is completely de-energized.

3. Open Cabinet Door: Open the control cabinet door and test I/O circuits to confirm power is off.

4. Locate Faulty Relay: Find the faulty relay on the EXHS board.

5. Prepare Protection: Place a rag or other nonconductive barrier below the board.

6. Remove Relay:

• Carefully snap off the clip holding the relay.

• Pull the relay out of its socket.

7. Install New Relay:

• Orient the replacement relay correctly and push it into the socket.

• Carefully snap the holding clip back into place.

8. Restore Power: Close the cabinet door, restore power to the excitation system following procedures, and test operation.