EEA-PAM-561-A-33 by Vickers

The EEA-PAM-561-A-33 power amplifier board is manufactured by Vickers and belongs to the EEA-PAM Power Amplifiers series. Installed in hydraulic control racks, the board interfaces between a machine controller and a proportional valve, scaling low-level command signals from PLCs or analog controllers into regulated coil current so that pressure, flow, or position can be adjusted precisely inside automated motion systems. It uses pulse-width-modulated drive techniques to limit valve hysteresis and offers onboard test points for diagnostics.

In typical operation, the card draws a control rail of 24 VDC and its total power consumption does not exceed 50 W, allowing it to reside in crowded enclosures without excessive heat load. The logic stage itself needs only 50 mA from the internal supply. Command interfaces accept either a differential ±20 mA current loop or a voltage reference of ±10 V; the voltage channel presents 47 k? input impedance while the current path terminates into a small burden resistor. A PWM output stage then converts the reference into solenoid current, and with reverse-polarity protection, the board tolerates wiring mistakes. At zero input, the load still sees 1.4 A, which maintains minimal pilot flow before active control begins.

During closed-loop tuning, the test points provide additional diagnostic signals. Mp1 feeds the drive monitor through an impedance of 10 k?, and Mp2 spans from minus to plus ten volts at full valve stroke for dynamic feedback. The current input loop is standardized on 100 ?, matching most PLC analog output cards, while the power section can deliver up to 1.8 A to the solenoid for full actuator authority. The auxiliary rails supply ±15 VDC for external sensors, and a 5 mA reference current together with an isolated ±10 VDC reference voltage simplifies position transducer excitation. This arrangement supports local sensor excitation without increasing back-plane load.