VT-VRPA1-150-1X/V0/0

The VT-VRPA1-150-1X/V0/0 is an electric amplifier card produced by Bosch Rexroth Indramat within the VT-VRPA Electric Amplifiers series. As a plug-in Euro-format module, it conditions command and feedback signals to drive proportional solenoids in hydraulic valves used across automated machinery. By converting low-level control voltages from a PLC into regulated current, the card allows precise modulation of hydraulic pressure or flow without mechanical adjustment.

The command socket accepts a full-scale input of +6 V, so a controller can vary the output from zero to maximum solenoid excitation within this limited range; negative voltages are ignored on this terminal. In contrast, the actual-value socket generates a feedback signal of -6 V, providing the PLC with a direct representation of valve position or pressure. A current input resistance of 100 Ω keeps the drive compatible with standard ±10 mA signal sources while minimizing loading on upstream electronics. Internally, a square-wave oscillator runs at 2.5 kHz with a tolerance of ±10%, establishing the pulse-width modulation carrier that the amplifier uses for current regulation. All stages are powered from the machine bus, which must deliver 24 V DC; the card contains its own regulators and fuse to protect downstream circuitry.

The onboard supply is stabilized to ±9 V with a 1% tolerance, so reference circuits remain stable even when the cabinet voltage fluctuates. Output current to the proportional solenoid reaches 2.2 A within a 10% margin, matching a coil resistance of 5.4 Ω and ensuring that the magnetic force tracks the command voltage. The W/x diagnostic socket has a loop impedance of 1 kΩ, allowing signal integrity to be checked without interrupting operation. Overcurrent events are limited by a time-delay fuse rated at 2.5 A, preventing damage to the card or field wiring during short circuits or miswiring.