VT 2000 proportional amplifiers are Eurocard-format electronic amplifiers for controlling direct or pilot-operated proportional pressure control valves that do not use electrical position feedback, using a clocked current output stage to drive the solenoid.
They accept a differential command input (0 to +10 V) for systems with separate reference potentials and also support an additional command channel that can be generated from an external potentiometer using an internal regulated +9 V reference. The command signals are summed, limited by a front-panel maximum-command attenuator, and then shaped by a ramp generator with separately adjustable up and down ramp times (with selectable ramp-time ranges and an option to force ramps to a short minimum). An adjustable bias current can be added to the commanded value, and the output includes a selectable dither frequency to improve proportional solenoid behavior while providing test points for command value and actual current. The series operates from a 24 VDC supply (within the specified tolerance) and includes protective functions such as reverse-polarity protection for the supply and short-circuit protection of the solenoid cable.
