IS220SRTDH2A is a Simplex Resistance Temperature Device Input Terminal Board Manufactured and Designed by General Electric as part of the Mark VIe Series used in GE Distributed Turbine Control Systems. The Simplex Resistance Temperature Device (RTD) Input (SRTD) terminal board is a compact RTD terminal board, designed for DIN-rail or flat mounting. The board has eight RTD inputs and connects to the PRTD I/O processor. High-density Euro-block type terminal blocks are mounted to the board. An on-board ID chip identifies the board to the I/O processor for system diagnostic purposes. In the Mark* VIe systems, the PRTD I/O pack works with the SRTD. The I/O pack plugs into the DC-37 pin connector and communicates with the controller over Ethernet. Only simplex systems are supported.
INSTALLATION:
The SRTD and a plastic insulator mount on a sheet metal carrier that mounts on a DIN rail. Optionally the SRTD and insulator mount on a sheet metal assembly that bolts directly to a cabinet. The eight RTDs are wired directly to the Euro-style box-type terminal block, which has 36 terminals and is available in two types. Typically #18 AWG wires (shielded twisted triplet) are used. The I/O cable shield terminal uses an external mounting bracket supplied by GE or the customer. Terminals 25 through 34 are not connected. E1 and E2 are mounting holes for the chassis ground screw connection (SCOM).
OPERATION:
The terminal board supplies a 10 mA dc multiplexed (not continuous) excitation current to each RTD, which can be grounded or ungrounded. The eight RTDs can be located up to 300 m (984 ft) from the turbine control cabinet with a maximum two-way cable resistance of 15. The onboard noise suppression is similar to that on the TRTD. The RTD inputs and signal processing are illustrated in the figure. The A/D converter in the PRTD pack samples each signal and the excitation current four times per second for normal mode scanning, and 25 times per second for fast mode scanning, using a time sample interval related to the power system frequency. Linearization for the selection of 15 RTD types is performed by the processor.