IS200TRTDH1D - RTD Input terminal board

Functional Description

IS200TRTDH1D Overview

IS200TRTDH1D is an RTD Input terminal board developed by GE. The RTD Input (TRTD) terminal board accepts 16 three-wire RTD inputs. These inputs are connected to two barrier-type terminal blocks. Surge and high-frequency noise are protected by noise suppression circuitry on the inputs. TRTD communicates with one or more I/O processors, which convert the inputs to digital temperature values and send them to the controller. TRTDH1D is a simplex board with two DC-type connectors for PRTD and normal scans. TRTDH1D works with the PRTD I/O pack in the Mark VIe control system and only supports simplex applications. Two PRTD packs connect to the TRTD, providing a total of 16 inputs.

Characteristics

• Number of channels: Eight channels per terminal board
• RTD types:
  • 10, 100, and 200 ? platinum
  • 10 ? copper
  • 120 ? nickel
• Span: 0.3532 to 4.054 V
• Maximum lead resistance:
  • 15 ? maximum two-way cable resistance
  • High/low (hardware) limit check
  • High/low (software) system limit check
• Fault detection: Failed ID chip

IS200TRTDH1D Features

• The TRTD board comes in four different versions. This variant has two DC-type connectors and is a simplex board.
• A PRTD board is connected to the PCB. Two terminal strips on the board can be disconnected for maintenance. There are twenty-four screw connections on each of these strips, allowing for eight 3-wire RTD inputs. Noise suppression circuitry is built into each input. This guards against both high-frequency noise and surge.
• The board also includes two female 37-pin cable connectors (JA1 and JB1) that can be used to link it to a PRTD board for input reading. The controller receives the inputs after they have been converted to digital temperature values.
• Both software system limit checking and hardware limit checking are included in the PCB. There are no jumpers or configurable hardware on the board. One edge of the board is notched, and two corners are notched. In the body of the board, there are two oval cutouts for screw mounting.

Installation

Wiring Instructions

• Connect the wires for the 16 RTDs directly to the two terminal blocks on the terminal board. Each block is held together by two screws and has 24 terminals that accept wires up to #12 AWG. Each terminal block has a shield terminal strip connected to the chassis ground. The double-shielded wire must be used.
• All shields must be terminated at the shield terminal strip. End shields are located at the end device.
• TRTDH1B in a TMR Mark VI control system provides redundant RTD inputs by fanning the inputs to three VRTD boards in the R, S, and T racks. The inputs meet the same environmental, resolution, suppression, and function requirements and codes as the TRTDH1C terminal board.

Operation

TRTD Excitation Current

• TRTD provides a 10 mA DC multiplexed (not continuous) excitation current to each grounded or ungrounded RTD. With a maximum two-way cable resistance of 15, the 16 RTDs can be located up to 300 m (984 ft) from the turbine control cabinet.

I/O Processor Sampling

• The I/O processor's A/D converter samples each signal and excitation current four times per second in normal mode scanning and 25 times per second in fast mode scanning, with a time sample interval related to the power system frequency. The linearization for the 15 RTD types is done by software. Out-of-range values detect RTD open and short circuits.

Channel Management

• To avoid adverse effects on other input channels, an RTD that is determined to be outside the hardware limits is removed from the scanned inputs. Repaired channels are automatically or manually reinstated in 20 seconds. At signal entry, all RTD signals have high-frequency decoupling to the ground.

Redundant Pacemakers

• The I/O processor's RTD multiplexing is coordinated by redundant pacemakers so that the loss of a single cable or I/O processor does not result in the loss of any RTD signals in the control database.