ABB IMHSS03

Product Features

ABB IMHSS03 obtains position feedback from the hydraulic actuator via a linear variable differential transformer (LVDT), compares it with the position command sent by the MFP, and drives the servo valve or I/H converter to achieve closed-loop control, ensuring that the throttle valve position precisely matches the command.

ABB IMHSS03 is equipped with high-resolution analog-to-digital and digital-to-analog converters, enhancing signal processing accuracy, optimizing LVDT signal conditioning capabilities, and improving position detection accuracy.

ABB IMHSS03 can automatically tune the demodulator gain, simplifying the commissioning process and improving the response speed of the control loop.

ABB IMHSS03 supports redundant LVDT interfaces (compatible with AC or DC LVDTs) and redundant servo valve outputs (with the option of dual valves operating simultaneously or a primary/standby mode), enhancing system reliability.

ABB IMHSS03 provides an I/H converter interface, supporting 4-20mA or 20-160mA output, with digital input and digital output capabilities.

ABB IMHSS03 displays operational status (normal, calibration, fault, etc.) via panel LED indicators, supports diagnostic testing to detect hardware faults, and can report error information via function codes.

Product Using Principle

ABB IMHSS03 along with the multifunction processor module and frequency counter module, forms a closed-loop system for turbine speed control. The working principle is as follows:

Command transmission: The MFP module sends position commands to the IMHSS03 module via the I/O expansion bus based on the set turbine speed target value.

Drive Output: After receiving the command, the IMHSS03 converts the digital command into an analog signal via a D/A converter, drives the servo valve or I/H converter, and controls the hydraulic actuator to adjust the throttle valve opening.

Feedback Detection: The LVDT measures the position of the hydraulic actuator, generating a differential voltage proportional to the position. The IMHSS03 converts this into a digital signal via a demodulator and A/D converter, and feeds it back to the MFP.

Speed regulation: The FCS module counts pulses from a magnetic sensor on the turbine shaft to measure turbine speed and sends the data to the MFP. The MFP adjusts the position command sent to the IMHSS03 based on the deviation between the speed feedback and the target value, forming a closed-loop control system.

Product Parameter

The following detail is for ABB IMHSS03 Hydraulic Servo Module.

LVDT Input (Secondary):

4 analog inputs, 2 sets of LVDT secondary (2 secondaries per set), 24Vpp, ±7V common-mode voltage, 10kΩ differential input impedance.

LVDT Output (Primary Excitation):

2 analog outputs, frequency 400Hz-15kHz, voltage 2.1-18Vpp (corresponding to minimum impedance 15-120Ω).

Servo Valve Output:

4 analog outputs (2 redundant groups), current ±8-±64mA (corresponding to maximum coil impedance 750-93Ω).

I/H converter output:

1 analog output, 4-20 mA (maximum impedance 300 Ω) or 20-160 mA (maximum impedance 15 Ω).

Digital input:

3 optically isolated inputs (250 VDC), conduction voltage ≥18 VDC, forward current 2.8 mA (nominal).

Digital output:

1 optically isolated open-collector output (250 VDC), conduction voltage 2.4 VDC (current 250 mA), cutoff voltage 24 VDC (leakage current 10 μA).