IS200VTCCH1C - THERMOCOUPLE CARD

Functional Description

The IS200VTCCH1C is a Thermocouple Processor Board developed by GE as part of the Mark VI series. The thermocouple processor board (VTCC) accepts 24 thermocouple inputs of types E, J, K, S, or T. These inputs are connected to two terminal blocks on the TBTC terminal board. Cables with molded connectors connect the terminal board to the VME rack, which houses the VTCC thermocouple processor board. The TBTC can provide control in both simplex (TBTCH1C) and triple modular redundant (TMR) modes (TBTCHIB).

IS200VTCCH1C Characteristics

• Number of channels: Each terminal board and I/O board has 24 channels.
• Thermocouple types: E, J, K, S, T thermocouples, and mV inputs.
• Span: -8 mV to +45 mV.
• A/D converter Sampling type: A/D converter with a resolution of 16 bits (instead of 14 bits).
• CJ compensation:
  • The temperature of the reference junction was measured twice on each TC terminal board (optional for remote CJs).
  • There are six cold junction references on the TMR board.
• Cold junction temperature accuracy: Cold junction accuracy is 2 °F.

IS200VTCCH1C Features

• As a thermocouple input board, the component takes twenty-four thermocouple inputs via terminal boards such as the TBTC and DTTC. The board only accepts T, S, K, J, and E thermocouples.
• The MKVI is part of the speedtronic range of gas and steam turbine management, which began with Mark I in the 1960s and has been extended over several decades with Mark VI and Mark VIe. The Mark VI is equipped with a central control module that is linked to an Operator Interface. This Operator Interface allows end-users to view alarm states and system data via a Windows platform PC-based interface.
• The board also accepts mV inputs with a range of -8mV to +45mV.
• The board does not support thermocouples of the B, N, or R kinds, or mV input ranges of -20mV to -9mV or +46mV to +95mV; if these ranges are required, a VTCCH2 board is needed.
• The board has two backplanes and four additional board connectors. Other connectors are constructed from conductive dots or traces.
• It contains hundreds of capacitors and resistors that are numbered and have reference designators. The board also includes diodes, inductor coils or beads, and TP test points.
• The board has a large number of integrated circuits, including dual-port SRAM, FPGAs, CMOS static RAM, and digital signal processors.
• The front faceplate contains three LED components:
  • ""Run"" (green LED)
  • ""Fail"" (red LED)
  • ""Status"" (orange LED)

Installation

Installation Instructions

• Turn off the VME processor rack.
• Insert the VTCC board and use your hands to push the top and bottom levers in to seat the board's edge connectors.
• Tighten the captive screws on the front panel's top and bottom.

Cable connections to the TBTC terminal boards are made at the lower J3 and J4 connectors on the VME rack. To secure the cables, these are latching connectors. Start the VME rack and look at the diagnostic lights on the front panel.

Operation

The TBTC's 24 thermocouple inputs can be grounded or ungrounded. They have a maximum two-way cable resistance of 450 and can be located up to 300 m (984 ft) from the turbine control cabinet. On the terminal board, there is high-frequency noise suppression as well as two cold junction reference devices. VTCC performs software linearization for individual thermocouple types. A thermocouple that is found to be outside of the hardware limits is removed from the scanned inputs to avoid adverse effects on other input channels.

Cold Junctions

• If both cold junction devices are within their configurable limits, the average of the two is used to compensate for cold junctions. If only one cold junction device falls within the configurable limits, it is used for compensation. If neither cold junction device meets the configurable limits, the default value is used.
• Using the filtered calibration reference and zero voltages, the thermocouple and cold junction inputs are automatically calibrated. Per VTCC, two cold junction references are used, one for connector J3 and one for connector J4.
• Each reference can be either remote (from the VME bus) or local. Then, all references are treated as sensor inputs (for example, averaged, limits configured). The two references, one local and one remote, can be mixed. Cold junction signals enter signal space and can be monitored.
• The average of the two is usually used. Acceptable limits are set, and if a cold junction exceeds the limit, a logic signal is generated. A one-degree Fahrenheit error in cold junction compensation results in a one-degree Fahrenheit error in TC reading.