Product Description:

The 7425AC is a DC servo amplifier manufactured by Copley Controls in the DC Servo Amplifiers series. It converts command voltages from a motion controller into regulated armature current for brushed or brushless DC motors. By closing the current loop within the amplifier, the module supplies precise torque commands, enabling accurate speed and position regulation on indexing tables, conveyors, and other industrial automation axes.

During continuous operation, the amplifier delivers a sustained output of 10 A, while a short-term output of 20 A can be applied for up to 2 seconds to overcome static friction or accelerate loads. A PWM carrier set at 25 kHz limits ripple and audible noise, and the full-bridge transistors have an on-state resistance of 0.15 Ω to minimize conduction loss. When the enable line is asserted, the power stage responds in 1 ms, allowing tight coordination with upstream safety relays. For diagnostic purposes, the current monitor provides 2 A/V, so a voltmeter can display real-time motor current. The design supports motors with inductances down to 400 µH, ensuring stable current control even with low-inductance windings. An inrush current of 37 A and a mains draw of 16 A must be accommodated by appropriately sized cabinet breakers. Logic transitions register above a 2.5 V threshold, and the reference input accepts up to ±20 V.

The small-signal bandwidth reaches -3 dB at 3 kHz, so current loops track the command changes required by high-performance positioning stages. An internal dissipation path rated at 61 W keeps semiconductor junction temperatures within limits during sustained modulation. Voltage safeguards disconnect the bridge when the DC bus exceeds 390 VDC or falls below 45 VDC, preventing component stress and erratic torque production if the upstream supply drifts.