IS200STAOH2A - Simplex Analog Output Terminal Board

Functional Description

IS200STAOH2A is a Simplex Analog Output Terminal Board manufactured and designed by General Electric as part of the Mark VIe series used in Distributed Control Systems. Compact analog output terminal boards are available, such as the Simplex Analog Output (STAO) terminal board, which is made for flat or DIN-rail mounting.

Eight 0-20 mA analog outputs on STAO are powered by the PAOC I/O pack. Similar to the TBAO terminal board, the onboard circuitry and noise reduction are present. The board is equipped with high-density Euro-block style terminal blocks for connecting to the customers' devices.

The board is identified to the I/O processor by an onboard ID chip for system diagnostics. The D-type connector is used to connect the I/O pack, which uses Ethernet to talk to the controller.

Installation

The STAO and a plastic insulator are mounted in a panel or on a DIN-rail-mounted sheet metal carrier. The STAO plus insulator mount can also be attached to a sheet metal assembly that is bolted directly to a cabinet. Driven equipment can be placed up to 300 meters (984 feet) away from the turbine control cabinet and shouldn't have a resistance greater than 900.

There are two varieties of Euro-block terminal blocks:

• An unpluggable mount terminal block with 36 terminals is present on STAOH1.
• A permanently installed terminal block with 36 terminals is present on STAOH2.

As seen in the following diagram, the eight analog outputs are attached directly to the terminal block. For the SCOM connection, there are two screws. Typically, shielded twisted pair (#18 AWG) wires are utilized. An external mounting bracket supplied by GE or the client is used by the I/O cable shield termination. The mounting holes E1 and E2 are for the chassis ground screw connection (SCOM). To save cabinet space, DIN-type terminal boards can be stacked vertically on the DIN rail.

Operation

Eight analog control current outputs are supported by STAO. The voltage drop across the current sense resistor in the local loop is detected for each output, and the signal is transmitted back to the I/O processor that regulates the current. Each output's surge is suppressed and high-frequency noise is reduced by filters close to the signal exit point. The D/A converter and drivers that produce the regulated currents are found in the I/O processor.