The IS200EROCH1ADD is an Exciter Regulator Options Card (EROC) manufactured by GE Energy as part of the EX2100™ excitation control system. This board is used in both simplex and redundant regulator control applications, as well as in full static excitation systems (including Alterrex™ applications). The EROC provides essential support functions for the regulator, including GE and third‑party field ground detection, keypad interface, tool (computer) interface, and power distribution to the Exciter Contact Terminal Board (ECTB). In redundant regulator configurations, the IS200EROCH1ADD also handles ISBus communication between the M1, M2, and C control sections and provides redundancy management signals.
The IS200EROCH1ADD mounts in a single slot of the IS200ERBP Exciter Regulator Backplane (ERBP) for simplex systems, or in the IS200ERRB Exciter Regulator Redundant Backplane (ERRB) for redundant systems. It is also used in full static control systems, where it installs into the IS200ESBP Exciter Simplex Backplane (ESBP) or the IS200EPBP Exciter Power Backplane (EPBP) for Alterrex redundant applications. The board is a double‑height (6U) Eurocard with 96‑pin P1 and P2 backplane connectors and a front panel with multiple interface connectors.
The suffix ADD indicates a specific revision and factory configuration (EROCH1, with A as a base designator and DD as further modifiers). This version maintains full backward compatibility with all EX2100 regulator and static control systems. The board contains no fuses or test points and is designed for high reliability in industrial excitation environments.
Functional Description
The IS200EROCH1ADD serves as a multifunction option card that expands the capabilities of the EX2100 regulator control. It performs the following key functions:
Ground Detector Interface – Supports either a GE ground detector (via the EXAM attenuator module) or a third‑party ground detector (via the IS200ERGT terminal board). The board provides a 9‑pin connector for the ground detector, carrying power amplifier output, sense signals, and alarm inputs. In simplex regulator systems, the M1 EROC controls the GE ground detector. In redundant systems, the M2 EROC (mounted in the ERRB) is used, and the ground detector cable is connected only to the redundant rack’s EROC.
Keypad Interface – The board provides an 8‑pin circular DIN connector on its faceplate for a local operator keypad (mounted on the control cabinet door). An additional keypad connector is also available on the backplane, allowing mounting flexibility. The EROC communicates with the keypad using RS‑232C at baud rates from 1200 to 38.4 K.
Tool (Computer) Interface – A 9‑pin D‑sub plug connector (RS‑232C) on the faceplate allows an external computer (e.g., a laptop running ToolboxST) to connect directly to the DSPX processor board through the EROC. This is used for commissioning, tuning, and diagnostics.
ECTB Power Supply – The board supplies isolated +70 V dc (P70) to the contact output section of the IS200ECTB Exciter Contact Terminal Board. This power is used for wetting customer relay contacts.
Redundant System Connections – In redundant regulator systems, the IS200EROCH1ADD provides a 9‑pin redundant connector that links the M1 EROC (in the ERBP) to the M2/C EROC (in the ERRB). This carries master select lines, K41 feedback and driver signals, and a cable diagnostic line.
ISBus Interface – The board features two jack connectors (ISBus) that connect the M1 rack to the M2/C rack. These carry differential transmit and receive signals (RS‑422/RS‑485) for system and local channels. The signals are used for high‑speed communication between the DSPX boards in the three control sections. A special crossover cable is required to route transmit lines to receive lines (Pin 1 to Pin 3, Pin 2 to Pin 6, etc.).
Full Static Control Support – In simplex static exciters (ESBP backplane), a single EROCH1 provides the keypad, tool, and ground detector interfaces. In redundant static Alterrex applications, two EROC boards are installed in the M1 and M2 EGDM slots of the EPBP backplane. One monitors the exciter field circuit for grounds, the other monitors the generator field circuit.
The board includes a green “Power” LED on the faceplate that illuminates when +5 V dc and ±15 V dc are present. There are no other on‑board indicators; all status is communicated via the control software or through the DSPX.
Hardware Characteristics
Size : Double‑slot height (6U) Eurocard.
Backplane Connectors : 96‑pin P1 and P2 (mate with ERBP, ERRB, ESBP, or EPBP).
Front Panel : Provides multiple connectors, a green LED, and captive screws with ejector tabs.
Connectors (Faceplate)
Connector | Type | Description |
Keypad | 8‑pin circular DIN | For local operator keypad (RS‑232C). |
Tool | 9‑pin D‑sub plug | For external computer (RS‑232C). |
J13 (ECTB) | 3‑pin mini connector | Supplies +70 V dc to ECTB contact output section. |
Ground Detector | 9‑pin receptacle | For GE EXAM or third‑party ground detector (via ERGT). |
Redundant | 9‑pin plug | Connects M1 to M2/C in redundant systems (carries master select, K41 signals, cable diagnostic). |
ISBus (2×) | Jack connectors (e.g., M1‑M2, M1‑C) | Differential communication lines between racks (RS‑422/485). |
LED Indicator
LED | Color | Function |
Power (on faceplate) | Green | Illuminated when digital +5 V dc and analog ±15 V dc power supplies are present. |
Pin Signal Tables (as per document)
Keypad Connector (8‑pin DIN)
Pin | Signal |
1 | KPP24 |
2 | KPTX232 |
3 | KPRX232 |
4 | KPCOM |
5 | KPCOM |
6 | KPCOM |
7 | KPP24 |
8 | KPRTS232 |
Tool Connector (9‑pin D‑sub plug)
Pin | Signal |
1 | Not connected |
2 | TLRX232 |
3 | TLTX232 |
4 | Not connected |
5 | TLICOM |
6 | Not connected |
7 | TLRTS232 |
8 | Not connected |
9 | Not connected |
Ground Detector Connector (9‑pin receptacle)
Pin | Signal | Description |
1 | M1_PA | GE ground detector power amplifier output |
2 | GDET_MAL | Third‑party ground detector malfunction |
3 | – | Not connected |
4 | SEN_ATT | GE ground detector input (attenuator end) |
5 | COM_GD | Third‑party ground detector common |
6 | GDET_ALM_II | Third‑party ground detector alarm fault |
7 | DIO_MON | Third‑party ground detector diode fault monitor |
8 | GDET_ALM_I | Third‑party ground detector alarm fault |
9 | SEN_AMP | GE ground detector input (amplifier end) |
Redundant Connector (9‑pin plug)
Pin | Signal | Description |
1 | SEL_P | Master select line positive |
2 | – | Not connected |
3 | – | Not connected |
4 | CABLE_RR | Redundant rack cable diagnostic output (M2) / input (M1) |
5 | K41_FDBKR | M1 K41 coil feedback |
6 | SEL_N | Master select line negative |
7 | CABLE_RTN | Return line for CABLE_RR |
8 | – | Not connected |
9 | K41_DRVR | M1 K41 driver |
ISBus Connector (jack, two locations – M1‑M2 and M1‑C)
Pin | Signal | Description |
1 | ISBTX_AP | Transmit signal positive |
2 | ISBTX_AN | Transmit signal negative |
3 | ISBRX_AN | Receive signal negative |
4 | – | Shorted to pin 5 |
5 | – | Shorted to pin 4 |
6 | ISBRX_AP | Receive signal positive |
7 | – | Not connected |
8 | – | Not connected |
Note: A crossover cable is required between EROCs: Pin 1 to Pin 3, Pin 2 to Pin 6, Pin 3 to Pin 1, Pin 6 to Pin 2.
Installation and Replacement Procedures
Handling Precautions
Static sensitivity – The IS200EROCH1ADD contains static‑sensitive components. Always wear a wrist grounding strap and handle the board at a grounded workstation. Store the board in its antistatic bag when not in use.
De‑energise before handling – Turn off power to the exciter (or the specific rack section) and verify zero voltage on all circuits before touching the board or connected cables. Follow local lock‑out/tag‑out procedures. Refer to GEH‑6631 (EX2100 Installation and Startup Guide).
Do not insert or remove with power applied – Doing so may cause equipment damage or personal injury.
Replacement Procedure (De‑energised System)
The EROC is not online‑replaceable in any application, including redundant regulator control. The rack must be de‑energised before replacement.
De‑energise the rack (e.g., ERBP, ERRB, ESBP, or EPBP) containing the EROC.
Open the cabinet door and test for zero voltage.
Label all cables connected to the EROC faceplate (keypad, tool, ground detector, ECTB, redundant, ISBus) to simplify reconnection.
Disconnect all cables.
Remove the board:
Loosen the top and bottom captive screws near the ejector tabs (do not remove them).
Raise the ejector tabs to unseat the board.
Using both hands, pull the board straight out.
Check the replacement board to ensure it is an IS200EROCH1ADD and that any configuration jumpers (none on EROC) are correct.
Slide the replacement board into the correct slot (e.g., the designated EROC slot in the backplane). Inserting into the wrong slot may damage electronics.
Seat the board by pressing firmly on the top and bottom of the faceplate simultaneously with your thumbs.
Tighten the top and bottom captive screws evenly to seat the board squarely.
Reconnect all cables to the correct faceplate connectors.
Close the cabinet door and restore power. Verify that the green Power LED illuminates.
When ordering the IS200EROCH1ADD, use the complete part number exactly as shown. The part number follows GE’s convention:
IS200 – Innovation Series, 200‑class.
EROC – Functional acronym: Exciter Regulator Options Card.
H1 – Version (EROCH1).
A – Base designator.
D – Modifier (e.g., coating, component variation).
D – Revision or additional modifier.
Warranty and Order Placement
Warranty replacements (within warranty period): Contact GE Industrial Systems Post Sales Service:
GE Industrial Systems
Post Sales Service
1501 Roanoke Blvd.
Salem, VA 24153‑6492 USA
Phone (US): +1 888 GE4 SERV (888 434 7378)
Phone (International): +1 540 378 3280
Fax: +1 540 387 8606
Spare parts or non‑warranty orders: Contact your nearest GE Sales or Service Office. Provide:
Note: All digits and letters in the part number are significant. GE may substitute later compatible revisions, but backward compatibility is assured.
Diagnostics and Maintenance
The IS200EROCH1ADD has no on‑board diagnostics other than the Power LED. The board’s health is monitored by the DSPX processor via the backplane. The DSPX reads the board’s ID device; a mismatch generates a hardware incompatibility fault. Loss of communication with the EROC (e.g., due to backplane problems) will be reported by the control system.
Common issues and checks:
Green Power LED off – No +5 V or ±15 V power from EPSM. Check EPSM output voltages, backplane connectors, and fuses in the power supply chain.
Keypad or tool communication fails – Verify RS‑232 cable connections and baud rate settings. Check that only one keypad is connected (the EROC supports two physical connectors but only one active device at a time).
Ground detector alarms – Use the ToolboxST software to read the ground fault status. Inspect the ground detector cable and the EXAM (or third‑party detector).
Redundant system faults (cable diagnostic) – The CABLE_RR signal (pin 4 of redundant connector) is used to detect presence of the cable between M1 and M2/C. If missing, check the redundant cable.
ISBus communication errors – Ensure the crossover cable is correctly wired (Pin 1 to Pin 3, Pin 2 to Pin 6, etc.). Verify that the cable is securely connected to both ISBus connectors.
No routine calibration or adjustment is required. Visual inspection for dust, corrosion, or loose connectors is recommended during periodic maintenance.
