IS220PRTDH1A: The Mark VIe RTD Input Pack, in Plain Terms

The IS220PRTDH1A is a Resistance Temperature Device (RTD) input pack from GE's Mark VIe Speedtronic control system. In a Mark VIe cabinet it is one of the small distributed I/O packs that clip directly onto a terminal board rather than living inside a card rack. Its job is narrow and important: read the resistance of the RTDs wired to the turbine and its auxiliaries, convert those readings into temperature data, and pass that data to the controller over the IONet Ethernet network.

Each PRTD pack pairs a processor board — the same base board used across the Mark VIe distributed I/O family — with an acquisition board dedicated to the RTD input function. The pack mounts on the RTD terminal board (the TRTD family) and connects through a DC-37 pin connector, while a three-pin connector feeds power and dual RJ45 ports carry the IONet traffic. One PRTD services up to eight three-wire RTD inputs; a TRTD terminal board can host two packs for up to sixteen RTDs. Each RTD, grounded or ungrounded, receives a 10 mA DC multiplexed excitation current, and the pack's A/D converter samples every channel four times per second in normal mode (25 times per second in fast mode).

Before You Replace the Pack: Diagnose the Whole RTD Loop

This is the section worth reading twice. On a temperature input pack, the symptom that looks exactly like a failed IS220PRTDH1A is very often something upstream of it. A single channel reading open, shorted, or wildly off is much more likely to be the RTD element or its field wiring than the pack itself, because the pack excites and reads each channel through the same shared circuitry — if seven channels are healthy and one is not, suspect that one loop first.

What usually fails that looks like a dead PRTD

• The RTD sensor itself. RTD elements drift, open up, or short after thermal cycling. Compare the suspect reading against a known-good reference or an adjacent sensor at the same location.
• Field wiring and lead resistance. The three-wire scheme compensates for lead resistance only within limits — the two-way cable resistance must stay at or below about 15 ohms, and the RTDs can sit up to 300 m (984 ft) from the cabinet. A corroded terminal, a loose ferrule, or a damaged run skews the reading.
• The TRTD terminal board. Check the screw terminals and the board revision before condemning the pack.
• Power and IONet. A pack that is dark, or missing from the controller's I/O list, is often a power-feed or network problem — inspect the three-pin power input and the Ethernet cabling and switch before assuming the electronics died.

Read the pack's LEDs before you order. The front panel carries a Power indicator, an ATTN (attention) indicator, and link LEDs for the two Ethernet ports. A lit ATTN or a diagnostic alarm in ToolboxST frequently points at a configuration mismatch or a field fault rather than a bricked pack.

Reading the IS220PRTDH1A Part Number

GE's Mark VIe part numbers are built in blocks. IS220 marks a distributed I/O pack assembly; PRTD is the functional code for the RTD input pack; and the trailing H1A is the group-and-revision suffix. As hardware revisions advance the letters step forward (for example H1A to H1B), so an H1A and an H1B are the same functional pack at different revision levels. When you order a replacement, match the full suffix and revision to what is installed. For a fuller walkthrough of the scheme, see our GE Speedtronic Part Number Decoder.

Related Mark VIe Temperature and I/O Packs

The PRTD is one member of a larger distributed I/O set. Its thermocouple counterpart is the PTCC pack; other neighbors handle analog and discrete I/O. If you are working across control generations, our guide on Mark V vs Mark VI: DS200 to IS200 explains how the older board-in-rack architecture gave way to today's pack-on-terminal-board design. You can also browse the full range of GE Mark VI IS200 Boards and GE Speedtronic Turbine Control Boards.

What to Send With Your Quote Request

• The complete part number including suffix — IS220PRTDH1A — and the revision printed on the label.
• A clear photo of the pack label if you can take one.
• Your turbine model and Mark VIe control generation.
• Quantity needed and how urgent the requirement is.

These details let us match the exact revision and confirm compatibility with your TRTD terminal board.

Request a Quote for the IS220PRTDH1A

This IS220PRTDH1A is offered as a used unit, cleaned and tested, and backed by our warranty as stated below. Use the Request a Quote button to send your requirement — we reply within 24 hours, ship worldwide on DDP terms, and accept purchase orders from qualified organizations.