GE IS200ECTBG1A Exciter Contact Terminal Board

The IS200ECTBG1A is an Exciter Contact Terminal Board designed by General Electric (GE) for its EX2100™ Excitation Control System. This board is the version within the ECTB series specifically used for redundant control systems, primarily handling contact output and input signals for the excitation system. The IS200ECTBG1A board, controlled by the EMIO board (Exciter Multi-function Input/Output Board), provides trip relay outputs and general-purpose relay outputs, while also monitoring auxiliary contact inputs from field devices.

In a redundant control system, the IS200ECTBG1A receives signals from the M1, M2, and C controllers, controlling the trip relays via a two-out-of-three contact voting circuit, ensuring high system reliability and fault tolerance. The relay drive circuits on the board are powered by 24 V dc, while the customer's external circuits use a nominal 125 V dc supply. The contact input section uses a 70 V dc wetting voltage, indicates contact status via LEDs, and distributes the signals to the three controllers.

The IS200ECTBG1A board includes two trip relay groups (K1M1, K1M2, K1C and K2M1, K2M2, K2C, three relays per group), four general-purpose relays (K1GP, K2GP, K3GP, K4GP, each driven by three inputs voting for a single coil), eight contact input channels (six auxiliary + 52G + 86G), two removable terminal blocks (TB1 and TB2), three 25-pin Sub-D connectors (J405, J408, J415), and two 70 V dc power input plugs (J13M1 and J13M2). The board design meets industrial-grade standards and is suitable for critical protection and control applications in power plant excitation systems.

II. Main Functions

The primary functions of the IS200ECTBG1A include, but are not limited to, the following:

1. Trip Relay Outputs (Redundant Control)

The IS200ECTBG1A board contains two groups of trip relays, each group driven by inputs from the M1, M2, and C controllers and controlled via a two-out-of-three contact voting circuit. This design ensures that even if a single controller fails, it will not cause a false trip or a failure to trip, significantly enhancing system reliability.

• Trip Relay Group 1: K1M1, K1M2, K1C

• Trip Relay Group 2: K2M1, K2M2, K2C

The contacts of the three relays in each group are connected in parallel to form the voting circuit output. These relays are typically used to drive the customer's external lockout devices. Relay characteristics are as follows:

• Customer Power: Nominal 125 V dc

• Contact Rating (Resistive Load): 5 A @ 28 V dc / 0.5 A @ 120 V dc

• Contact Rating (Inductive Load, L/R=0.007s): 2 A @ 28 V dc / 0.2 A @ 120 V dc

• With Suppression: 0.5 A @ 120 V dc

• External suppression provided by customer

• Agency Approvals: UL, CSA

2. General Purpose Relay Outputs (Redundant Control)

The IS200ECTBG1A board contains four general-purpose relays. Each relay's single coil is driven by inputs from the M1, M2, and C controllers after two-out-of-three voting by the relay drive circuit. This design ensures the reliability of relay operation.

• General Purpose Relays: K1GP, K2GP, K3GP, K4GP

• Contact Type: Form-C (one normally open, one normally closed, common terminal)

• Customer Power: Nominal 125 V dc

• Contact Rating (Resistive Load): 2 A @ 28 V dc / 0.5 A @ 120 V dc

• Contact Rating (Inductive Load, L/R=0.007s): 1 A @ 28 V dc / 0.1 A @ 120 V dc

• External suppression provided by customer

• Agency Approvals: UL, CSA

3. Contact Input Monitoring

The IS200ECTBG1A board provides eight contact input channels, divided into three categories:

• Six Auxiliary Contact Inputs (Contact Input 1-6): From customer-provided external auxiliary contacts, used to monitor the status of various field devices.

• 52G Contact Input: Used to monitor the status of the generator breaker (52G) auxiliary contact.

• 86G Contact Input: Used to monitor the status of the lockout relay (86G) contact.

All contact inputs are wetted with a 70 V dc power supply, sourced from the J13M1 and J13M2 plugs (from the M1 and M2 controller power supplies, respectively). The allowable wetting voltage range is 63 to 84 V dc. The status of each contact input is indicated by an onboard red LED, and the signals are simultaneously distributed to the M1, M2, and C controllers for monitoring and protection logic within the excitation system.

4. Interfaces and Connections

The IS200ECTBG1A board provides various interfaces for connection to controllers and field devices:

• TB1 and TB2: Removable terminal blocks for connecting external wiring for trip relays, general-purpose relays, and contact inputs. Each terminal block has 24 terminals and is secured to the board with two screws.

• J405, J408, J415: Three 25-pin Sub-D connectors for connection to the EBKP backplane, which interfaces with the EMIO boards of the M1, M2, and C controllers.

• J13M1 and J13M2: Two power plugs for inputting the 70 V dc wetting voltage, sourced from the M1 and M2 controller power supplies, respectively.

  
  

III. System Applications

1. Application in EX2100 Redundant Control System

The IS200ECTBG1A is a dedicated terminal board for handling contact I/O within the EX2100 redundant excitation control system. Its roles within the system include:

• Trip Output: Receives trip commands from the M1, M2, and C controllers, drives the trip relays after two-out-of-three voting, and outputs to the customer's external lockout devices to implement safe shutdown of the generator or excitation system.

• General-Purpose Control Output: Receives general-purpose control commands from the three controllers, drives the general-purpose relays after voting, and is used to control various auxiliary devices such as alarms, indicators, and interposing relays.

• Status Monitoring: Monitors the status of auxiliary contacts from the field (e.g., breaker position, valve status, protection operation signals) and feeds the status information back to the controllers via the EMIO board for logic decision and monitoring.

• Electrical Isolation: Provides isolation between the internal circuits of the control system and external high-voltage circuits via relay contacts, protecting the control boards.

2. Typical Application Scenarios

• Trip circuits for synchronous generator excitation systems

• Alarms and status indication for excitation systems

• Breaker position monitoring

• Interface for protection lockout circuits

• Contact input/output in industrial process control

  
  

IV. Detailed Interface Description

1. Terminal Blocks TB1 and TB2

TB1 and TB2 are removable 24-terminal blocks for connecting all external wiring for relay outputs and contact inputs. Terminal assignments are as follows (TB1 screws 1-24, TB2 screws 25-48):

2. J13M1 and J13M2 Power Plugs

These 3-pin plugs provide the 70 V dc wetting voltage:

3. J405, J408, J415 Connectors

These three 25-pin Sub-D connectors connect to the EBKP backplane, corresponding to the M1, M2, and C controllers respectively. Pin assignments for J405 (to M1) as an example:

V. Installation and Replacement

1. Mounting Location

The IS200ECTBG1A board is mounted inside the EX2100 excitation control cabinet, secured to a mounting plate with screws. Ensure sufficient space around the board for wiring and maintenance access during installation.

2. Offline Replacement Procedure (Exciter De-energized)

1. De-energize and Discharge: Turn off power to the excitation system. Follow the complete de-energizing procedures outlined in GEH-6631 and adhere to all local Lock-out/Tag-out practices. Allow time for capacitors to discharge.

2. Open Cabinet Door: Open the control cabinet door and test electrical circuits to ensure power is off.

3. Label Cables: Verify all cables are correctly labeled for easy reconnection.

4. Disconnect Cables:

• Remove J13M1 and J13M2 power plugs.

• Disconnect J405, J408, J415 signal connectors.

• Loosen the two screws securing TB1 and TB2, and remove the terminal blocks (leaving external wiring attached).

5. Remove Old Board: Remove the screws holding the ECTB board and take out the old board.

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

7. Reconnect:

• Reinstall TB1 and TB2 terminal blocks, tighten retaining screws.

• Reconnect J405, J408, J415 connectors.

• Reconnect J13M1 and J13M2 power plugs.

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

3. Online Relay Replacement (Redundant Systems Only, Not Recommended)

In a redundant control system, if a specific trip relay (e.g., K1M1) fails, it is possible to identify the faulty relay using diagnostic tools and replace it while the system is energized. However, this operation carries significant risk and extreme caution is required:

• Risks: All boards within the control cabinet are energized. Improper operation can lead to equipment damage, personal injury, or an exciter trip.

• Steps:

1. Use the Toolbox diagnostics to identify the faulty trip relay.

2. Open the control cabinet door and locate the faulty relay on the ECTBG1 board.

3. Very carefully snap off the clip holding the relay in place.

4. Pull the relay out of the board.

5. Push in the replacement relay of the same type.

6. Carefully snap the retaining clip back onto the replacement relay.

7. Close the control cabinet door.

Caution: During online relay replacement, take extreme care not to drop any metal parts or tools into the cabinet.