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Key Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | IS220PAOCH1B |
| Function Code | PAOC (Analog Output/Input Combo) |
| Input Signals | 4-20 mA (HART), ±10 Vdc, Thermocouple (via TB) |
| Output Signals | 4-20 mA, Servo Valve Drive (Current), Relay |
| LVDT Interface | Excitation & Readback (Linear Variable Differential Transformer) |
| Communication | Ethernet (Mark VIe), IONet (Mark VI) |
| Power Supply | 24 Vdc Nominal (Nominal range 18-32 Vdc) |
| Terminal Board | Mates with IS200TBAIH1x / IS200STAIH1x series |
| Environment | -30°C to +65°C (Operating) |
| Certification | UL, CSA, ATEX (Zone 2), IECEx |
| Dimensions | Standard Eurocard form factor (fits in I/O carrier) |
Product Introduction
If you are running a GE Frame 6 or 7 gas turbine, you know that the Mark VIe system is the brain, but the IS220PAOCH1B is the nervous system. It’s the interface that actually talks to the hardware—reading your vibration probes, positioning your fuel valves via LVDTs, and handling those critical 4-20mA control loops. I’ve pulled these out of racks that have been baking at 50°C for a decade, and frankly, they are built like tanks. The conformal coating on the PCB is heavy-duty, designed specifically to survive sulfur-rich environments and high humidity without corroding the traces.The “C” in the part number is what you need to watch. It denotes a hardware revision that usually plays nicer with newer Ethernet-based architectures than the old serial-based packs. It handles high-current outputs (up to 200mA for some servo applications) which is a common failure point on lesser modules. If you’re replacing an older unit, don’t just assume it’s plug-and-play; the internal impedance and scaling might differ slightly from the ‘A’ or ‘B’ revisions you pulled out.
Quality SOP & Tech Pitfalls (The Reality Check)
The Lab Report (SOP):
Before we ship this, we don’t just wipe it off and box it up.
- Visual Inspection: We check the conformal coating for any flaking or burn marks near the power regulators.
- Connector Integrity: The JE and JF connectors (the ones mating with the terminal board) are inspected for bent pins—this is the #1 cause of “ghost” alarms.
- Live Loop Test: We hook it up to a simulator to verify the 4-20mA output accuracy against a Fluke 744 calibrator. We also test the LVDT excitation voltage to ensure it’s stable under load.
The Engineer’s Warning (Pitfalls):
Here is where people get burned. The IS220PAOCH1B has hardware jumpers (J1, J2, J5, J6) that configure the current output ranges (4-20mA vs. 20-200mA).
Field Horror Story: A tech swapped a failed pack with a new one but didn’t check the jumpers. The old one was set for 200mA to drive a specific Moog valve; the new one was factory-set to 20mA. Result? The turbine couldn’t stroke the valve, hit a overspeed trip, and shut down the plant. Always photograph the jumper settings on the bad card before you pull it.
Installation & Configuration Guide
This isn’t a “plug and pray” job. Follow the procedure.
- Pre-Installation:
- ⚠️ Safety First: Ensure the I/O carrier power is disconnected or the specific slot is de-energized if hot-swapping is permitted by your safety logic (rare for analog outputs driving servos).
- Photo Op: Take a high-res picture of the failing card’s jumpers and DIP switches.
- Removal:
- Unscrew the captive screws on the faceplate.
- Gently rock the card to release the standoff guides. Do not yank it; the connectors are tight.
- Configuration (Critical):
- Match the Jumpers: Before inserting the new
IS220PAOCH1B, move the shunts on J1/J2 (Current Select) and J5/J6 (Range) to match the old card exactly. Consult the GE manual (GEH-6721) if you aren’t sure, but matching the old hardware is usually the safest bet for a quick swap.
- Match the Jumpers: Before inserting the new
- Installation:
- Slide the pack into the slot. Ensure the top and bottom guides engage smoothly.
- Tighten the screws to seat the backplane connector firmly.
- Power-On & Testing:
- Restore power. Watch the LEDs. You want to see the “OK” LED solid green.
- Log into the HMI/Toolbox. Check for “Hardware Mismatch” alarms. If the revision doesn’t match the database, you may need to update the tool file.
Compatible Replacement Models
| Compatibility Tier | Model Number | Notes |
|---|---|---|
| ✅ Drop-in Replacement | IS220PAOCH1B | Exact match. Ensure firmware version matches the controller core. |
| ⚠️ Software Compatible | IS220PAOCH1A | Older revision. May require firmware downgrade or logic recompile. |
| ❌ Hardware Mod Required | IS220PAICH1B | Different pinout/signal type (Analog Input vs Output). Will not work. |
Frequently Asked Questions (FAQ)
- Q: Can I hot-swap this while the turbine is running?
- A: Technically, the Mark VIe supports redundancy (R, S, T cores). If you are swapping a pack in a redundant system, maybe. But if this pack is driving a solo servo valve, pulling it will cut power to the valve. That’s a trip. Only hot-swap if you have a triple-redundant setup and know exactly which core is active.
- Q: My replacement card shows a “Hardware Mismatch” alarm. What gives?
- A: The controller expects a specific revision ID. If you put a Rev B in a slot configured for Rev C, it throws a fit. You usually have to update the Tool File (TF) in the Toolbox software to recognize the new hardware revision.
- Q: What is the difference between PAOC and PAIC?
- A: Simple. PAOC (this model) handles Outputs (Control). PAIC handles Inputs (Monitoring). They look similar, but the circuitry inside is totally different. Don’t mix them up.
- Q: Does this come with the terminal board?
- A: No. This is just the “Pack” (the circuit board). The Terminal Board (TB) stays mounted to the cabinet backpanel. You just slide the Pack into the TB.
- Q: How do I know if the fuses are blown?
- A: There are no user-serviceable fuses on the front. If you have power but no output, or the LED is dead, the internal protection has likely blown. It’s usually cheaper to replace the board than to troubleshoot surface-mount fuses.
