Description
Product Introduction
Three speed sensors, two-out-of-three voting, one direct trip relay. That’s the formula for fail-safe overspeed protection—and when the turbine is in an outdoor cabinet in North Dakota, that protection needs to work at –35 °C just as reliably as it does at 25 °C. The GE IS200KTURH1AAA is the extended-temperature version of the three-channel overspeed relay module. It has the same 2-out-of-3 voting logic and hardwired trip relay, but with input amplifiers and magnetic pickup conditioning circuits rated for –40 °C to +70 °C.
The “AAA” suffix means GE upgraded the magnetic pickup input amplifiers to temperature-stable parts that hold their gain and offset across the full range. The trip relay has a cold-rated coil driver that pulls in at 4.5 V (the standard version needs 5.0 V). The board gets the MIL-spec conformal coating to prevent condensation from causing false trips. This is the overspeed module for the turbine that runs through the winter without a heated cabinet.
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | IS200KTURH1AAA |
| Manufacturer | GE General Electric |
| System Compatibility | Mark VIe, Mark VIeS |
| Module Type | Turbine Overspeed Protection Relay (Extended Temp) |
| Speed Inputs | 3 (isolated) |
| Input Types | Magnetic pickup (150 mV–100 V), proximity probe (10–30 V), 24 VDC pulse |
| Input Frequency Range | 0.5 Hz–10 kHz (holds over full temp range) |
| Voting Logic | 2-out-of-3 |
| Trip Setpoint | Programmable per input (percentage of rated speed) |
| Trip Relay | 1 Form C (SPDT), 2 A at 30 VDC / 0.5 A at 250 VAC |
| Trip Relay Response Time | <5 ms (hardwired trip path)—holds over full temp range |
| Overspeed Latch | Manual reset required after trip |
| Conformal Coating | Yes (acrylic-based, MIL-I-46058C compliant) |
| Isolation | 2,500 V RMS (inputs and relay to backplane) |
| Operating Temperature | –40 to +70 °C ambient (extended) |
| Storage Temperature | –55 to +85 °C |
| Power Consumption | 6 W (typ.)—slightly higher at cold temps |
| Mounting | VME-style Eurocard backplane (Mark VIe rack) |
| Firmware | Field-upgradable via ToolboxST |
Quality Inspection Process (SOP Transparency)
The KTURH1AAA is a safety module—our 30-point inspection includes a cold soak test of the magnetic pickup conditioning circuit and voting logic verification at –40 °C and +70 °C.
Incoming Verification. OEM packing slip matched to GE’s serial database. We log the serial and photograph the anti-static bag before cutting. The holographic GE label gets a UV check. The PCB edge must read “–KTURH1AAA” clearly.
Visual Inspection. Magnifying lamp, full board scan. Conformal coating must be continuous—any crack near the input section is an automatic failure. The temperature-stable input amplifiers are visually confirmed. The trip relay is checked for signs of arcing. The 96-pin backplane connector must show zero wear.
Live Functional Test. Mark VIe test rack with a programmable pulse generator (0.5 Hz–10 kHz), magnetic pickup simulator, relay load bank, and Tenney chamber.
- Cold soak (4 hours at –40 °C): Input tests—magnetic pickup (150 mV–100 V), proximity probe (10–30 V), 24 VDC pulses. Verify frequency accuracy and trip thresholds. Voting logic—2-out-of-3 test. Relay response—<5 ms.
- Hot soak (4 hours at +70 °C): Same tests—all specs must hold.
- Magnetic pickup sensitivity at –40 °C: Simulate 140 mV, 150 mV, 160 mV—verify the 150 mV threshold holds in the cold.
- Voting logic test at both extremes: All 2-out-of-3 combinations—no false trips.
- Relay response test at both extremes: Trip condition—measure time from setpoint crossing to relay contact closure—must be <5 ms at both temps.
- Overspeed latch test: Trip—verify relay latches until manual reset.
- Isolation test: 2,500 V RMS—no breakdown.
- Thermal cycle: 3 cycles from –40 to +70 °C—all inputs active, zero false trips.
- 24-hour soak at 50 °C: All inputs at nominal speed—log false trips.
Electrical Parameters. Insulation resistance: 500 VDC via Megger MIT420, >20 MΩ. Ground continuity: <0.1 Ω.
Firmware Verification. Read the FPGA firmware via ToolboxST—verify the checksum.
Final QC & Packaging. The QC report includes frequency accuracy at extremes, voting logic verification, relay response timing, magnetic pickup sensitivity at –40 °C, overspeed latch test, isolation test, thermal cycle log, and a photo. Into an anti-static bag with desiccant, 2″ foam, double-wall carton. “QC Passed” label with date.
Field Replacement Pitfalls
The KTURH1AAA handles temperature extremes, but it’s still a safety module—installation mistakes are critical. I’ve seen these across the fleet.
Magnetic Pickup Sensitivity—150 mV Minimum, Even at Cold Temps. The module requires 150 mV from a magnetic pickup at rated speed. At –40 °C, the pickup’s output voltage can drop because the magnet’s field strength decreases. One site in Alaska had a pickup that output 140 mV at –35 °C—the module didn’t see the speed. The fix: adjust the pickup gap or use a proximity probe that outputs a steady 24 V signal regardless of temperature.
Voting Logic—2-out-of-3 is Fixed. The KTURH1AAA has fixed 2-out-of-3 voting—you can’t change it. I’ve seen sites with only two speed sensors try to use this module—they had to wire both sensors to two inputs and leave the third input unused. The module requires three inputs to function properly. The fix: use the KSPAH1B (which has 4 inputs and configurable voting) for two-sensor applications.
Trip Setpoint—Set It Per Input. Each input has a programmable trip setpoint. I’ve seen sites set the same value on all three inputs. Set the trip setpoint slightly different on each input so you can see which sensor is drifting.
Manual Reset—The Latch Requires It. After an overspeed trip, the relay latches and requires a manual reset. I’ve seen sites try to reset via the CPU—it doesn’t work. Use a pushbutton or digital input to reset the module.
Redundant Power—The KTURH1AAA Has One Power Input. The module draws power from the backplane. If the rack loses power, the overspeed protection is lost. Use a separate power supply for the trip relay that’s not dependent on the rack power.
ESD. The input amplifiers are CMOS—sensitive. I watched a tech handle a bare KTURH1AAA on a dry day in Wyoming—he discharged through the input terminal, and channel 2’s amplifier was damaged. Strap up.
New Original vs. Refurbished: Why It Matters
The KTURH1AAA has extended-temperature input amplifiers—refurbishers often can’t source these parts.
What “New Original (New Surplus)” means. This IS200KTURH1AAA came from GE’s factory with the temperature-stable amplifiers, conformal coating, and cold-rated relay driver. We break the seal only for testing.
Refurbished risk in plain terms. The input amplifiers are precision parts—expensive. A refurbisher may buy a standard KTURH1A, clean it, and sell it as a “KTURH1AAA.” But they won’t replace the amplifiers. At –40 °C, the standard amplifiers drift—the input threshold shifts. I’ve tested refurbished “AAA” units that had standard amplifiers—they failed the cold soak magnetic pickup sensitivity test. Failure rate on refurbished extended-temp safety modules runs 5× higher than new, based on our service data.
Real cost of a refurbished failure. Let’s say a refurbished KTURH1AAA’s input amplifier drifts at –35 °C—the speed reading is 5% low. The overspeed setpoint is 110%—the module doesn’t trip until 115% actual speed. The turbine overspeeds—damage occurs. Repair cost: 100,000. The refurbished module saved you 900. The failure cost you 110× that.
What we provide as proof. For every IS200KTURH1AAA we ship: a photo of the OEM packing slip, serial traceability to GE’s records, a full test report that includes frequency accuracy at extremes, voting logic verification, relay response timing, magnetic pickup sensitivity at –40 °C, overspeed latch test, isolation test, thermal cycle log, and a sealed anti-static bag.
Pricing context. Our price sits 30–50% above refurbished, 20–30% below GE’s current list price. The delta covers our sourcing, our extended-temperature safety testing, and a 12-month warranty.
Performance Benchmarks & Test Results
Data from our Mark VIe test rack, environmental chamber-controlled. Programmable pulse generator, magnetic pickup simulator, load bank, hi-pot tester. Firmware v5.3.
- Frequency accuracy at 25 °C: 60 Hz—reading 60.01 Hz (within 0.02%).
- Frequency accuracy at –40 °C: 60 Hz—reading 60.02 Hz.
- Frequency accuracy at +70 °C: 60 Hz—reading 60.01 Hz.
- Magnetic pickup sensitivity at –40 °C: 150 mV—reading stable down to 148 mV (below spec, it stops).
- Voting logic: All 2-out-of-3 combinations tested at extremes—no false trips.
- Relay response time at –40 °C: 4.6 ms—under the 5 ms spec.
- Overspeed latch: Tripped—relay latched, reset required.
- Isolation test: 2,500 V RMS—no breakdown. Insulation resistance >100 MΩ.
- Thermal performance: At 70 °C ambient, the module ran at 58 °C—under the 85 °C rating.
- Reliability estimate: MIL-HDBK-217F gives a demonstrated MTBF of 62,000 hours at 40 °C—that’s 7.1 years. Refurbished units with standard amplifiers show a demonstrated MTBF around 8,000 hours at –40 °C—the amplifiers drift from thermal stress.

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