IS220PTURH1A (Rev D): the Mark VIe overspeed and speed-sensing pack

Shaft speed is the most safety-critical measurement on any turbine, and on a GE Speedtronic Mark VIe machine the Primary Turbine (PTUR) I/O pack is where that measurement is acquired and turned into the primary overspeed trip. This IS220PTURH1A in Rev D is offered used, cleaned and tested, with a one-year warranty. It mounts on the turbine terminal board, connects to the controller over one or two IONet networks, and exchanges signals through a DC-62 pin connector.

Speed sensing and primary overspeed, explained

The pack takes four passive magnetic speed pickups and derives a median speed. That median is used both for normal speed control and for the primary overspeed trip, giving the machine a protection path that does not depend on any single sensor. The input circuit is sensitive enough to register about 2 RPM, which lets the control distinguish a shaft barely rolling on turning gear from one that has truly stopped. Because these functions are protective, the pack's health is monitored continuously and reported to the controller through ToolboxST diagnostics.

Symptoms that mimic a bad PTUR (and how to tell the difference)

• Erratic or missing speed on one channel: almost always the magnetic pickup, its mounting gap or its cable. Re-gap or swap the sensor and re-check before ordering a pack.
• All channels wrong at once: look at the shared items, the terminal board, the DC-62 connector and the power feed, rather than assuming the pack's front end failed across every channel simultaneously.
• Overspeed trip with no real overspeed: noise on the pickup wiring or a grounding fault can inject false pulses; inspect shielding and cable routing.
• Pack offline in ToolboxST: an IONet cable, switch port or controller issue, not necessarily the pack; the pack runs from either Ethernet port, so test the alternate.
• Will not accept firmware: confirm auto-reconfiguration is enabled and the controller baseload matches; a configuration mismatch imitates a hardware failure.

What Rev D means and why the revision matters

IS220PTUR is the primary turbine function and H1A is the hardware group; Rev D is a later hardware revision of that group. Revisions capture running production changes, and while many are backward compatible, the reliable approach is to match the revision to the pack you are replacing, or to what your controller configuration calls for, rather than assume. Our GE Speedtronic Part Number Decoder explains each field of these IS220 numbers.

TTURH1C, STUR and the TRPA alternative

The PTUR normally pairs with the TTURH1C turbine terminal board and also works with the STUR board. In an alternative primary-trip arrangement, up to three PTUR packs can plug directly onto a TRPAH1A board, where each pack handles four speed inputs and the board provides solid-state primary trip relays; that arrangement does not carry the synchronizing, flame or main-breaker functions of the full TTUR wiring. Knowing which board your pack sits on tells you which signals it is responsible for.

Help us quote the right card the first time

Include the full part number (IS220PTURH1A), the revision (Rev D or the exact trailing letter on your label), a photo of the label, the turbine and Mark VIe control model, simplex or TMR, quantity and urgency. If the pack sits on a TRPA rather than a TTUR board, mention that too.

Start your quote request

This Rev D IS220PTURH1A is cleaned and tested. Request a Quote for a reply within 24 hours, worldwide DDP delivery and purchase orders accepted. Related boards are grouped in our GE Speedtronic Turbine Control Boards collection.

General Information about the Product
Part Number	IS220PTURH1A Mark VI IS220
Description	IS220PTURH1A By General Electric Rev D Input/Output Turbine Control System
Condition	used Clean and Tested. With 1 Year Warranty.