ABB IMHSS03 Hydraulic Servo Module

Description:

• The IMHSS03 Hydraulic Servo Module is a valve position con- trol module used in an INFI 90® system to control the speed of a turbine. It interfaces a servo valve or an I/H converter to an IMMFP01, IMMFP02 or IMMFP03 Multi-Function Processor Module. The multi-function processor (MFP) module controls the position of a steam or gas turbine throttle valve by sending a position demand to the hydraulic servo (HSS) module. The HSS module drives its outputs to open or close the throttle valve to match the position demand. The MFP module uses the IMFCS01 Frequency Counter Module to measure the turbine speed. The frequency counter module measures turbine speed by counting and timing pulses from a magnetic pickup on the turbine shaft. The MFP module uses this count to calculate turbine speed and calculate a new demand based on a set point.