IS220PRTDH1B: RTD Inputs Into the Mark VIe Controller

The IS220PRTDH1B shown here is a used, cleaned-and-tested RTD input pack for the GE Mark VIe platform. Like the rest of the PRTD family, it converts the resistance of field RTDs into temperature data and streams that data to the controller over the IONet — the everyday work of temperature acquisition on a Mark VIe-controlled turbine.

What sets the RTD pack apart from its thermocouple sibling is the front-end circuit: the PRTD sources a precise, multiplexed 10 mA DC excitation current into each RTD and measures the voltage that comes back, digitizing it with a 14-bit converter. One pack serves up to eight three-wire RTDs and mounts directly on an RTD terminal board, drawing power from a three-pin connector and communicating through two RJ45 IONet ports.

The TRTD Terminal Board and Scan-Rate Traps

The PRTD does not wire to the field directly — it plugs into a TRTD-series RTD terminal board, and that pairing matters more than most people expect. The terminal board carries the field terminations and the channel's transient protection and filtering, and it comes in revisions matched to how fast the pack scans:

• A standard-scan terminal board revision filters for the pack's normal sampling rate.
• A fast-scan revision uses lighter filtering so that fast-scan operation reads correctly.

Mounting a PRTD on an incompatible terminal board revision is reported by the system rather than silently tolerated, and while it will not physically damage anything, it will keep the channel from performing as intended. There are also simplex RTD terminal board variants in the S-series (SRTD) in addition to the T-series (TRTD). Distributor documentation describes the PRTD as a simplex pack; within the wider Mark VIe framework, distributed I/O supports simplex, dual, and triple-modular-redundant (TMR) control modes, the last using separate packs for the <R>, <S>, and <T> controllers. When you replace a PRTD, verify the terminal board type and revision as carefully as the pack itself.

Clear the Loop Before Condemning the Pack

Because the terminal board, wiring, and sensor are all in series with the pack, a wrong reading is often not the pack's fault. Check the RTD element against a neighbor, verify the two-way lead resistance is within about 15 ohms over a run that can reach 300 m (984 ft), inspect the TRTD terminals, and confirm power and IONet before ordering a replacement. The Power and ATTN LEDs plus ToolboxST diagnostics will usually separate a field fault from a genuine pack failure.

What the Suffix and Revision Tell You

IS220 identifies the distributed I/O pack, PRTD the RTD input function, and H1B the group and revision. The final letter tracks hardware revision level, so keep suffix and revision matched to the installed unit — and, as above, to the terminal board. See the GE Speedtronic Part Number Decoder for the full breakdown.

Related Resources and Boards

For the thermocouple equivalent, look at the PTCC packs; for the shift from the previous control generation, read Mark V vs Mark VI: DS200 to IS200. Our collections of GE Mark VI IS200 Boards and GE Speedtronic Turbine Control Boards hold the wider range.

Quote Request Essentials

• Complete part number and suffix (IS220PRTDH1B) with the label revision.
• A label photo, and the terminal board type/revision if known.
• Turbine model and Mark VIe generation.
• Quantity and urgency.

Request a Quote Today

This IS220PRTDH1B is used, cleaned and tested, and backed by the warranty noted below. Hit Request a Quote and we will reply within 24 hours. We ship worldwide on DDP terms and accept purchase orders.