EHH-AMP-702-K-20 by Vickers

The EHH-AMP-702-K-20 is an electronic amplifier module produced by Vickers as part of the Vickers Accessories series. The device is installed between a machine controller and a proportional solenoid, translating low-level reference currents into regulated drive energy for hydraulic valve actuation. Its purpose in industrial automation is to provide accurate, repeatable control of flow or pressure without loading the control circuitry, while keeping the power section close to the actuator to shorten field wiring.

The amplifier accepts a command current of 4-20 mA that is terminated across an internal 250 ? shunt, so a PLC can develop the reference with standard loop hardware. Internally generated PWM pulses at 1200 Hz modulate the output stage, and within this carrier the module delivers up to 1.6 A of coil current to the connected solenoid. Nominal power is supplied from 24 V DC, while the circuitry tolerates excursions up to 40 V DC without damage. Protective logic limits overall consumption to 35 W and incorporates reverse-polarity and short-circuit shutdown. A front-mounted LED switches on at 4 mA to confirm loop integrity, and the sealed enclosure meets IP67 for operation in areas exposed to oil spray and moisture.

The enclosure is molded from PA6 glass-reinforced plastic to minimize weight, and the complete unit weighs 0.07 kg. Electrical connection is made through a DIN-form plug base that matches the ISO 4400 pattern, and the integral cable gland is threaded Pg9 to accommodate typical multi-core valve leads. A 120 Hz dither signal is superimposed on the output to reduce hysteresis in the hydraulic spool. Installation requires no additional heat sink because power is distributed through the mounting face, and the housing isolates the electronics from fluid exposure while maintaining a sealed enclosure.