Product Description:

The 421CE DC servo amplifier is built by Copley Controls within the DC Servo Amplifiers series. By converting a ±170 V bus into accurately regulated motor current, it drives brushed or brushless servomotors that need fast torque response in pick-and-place heads, gantry axes, and coil winders. The amplifier fits into panel enclosures and responds to differential analog commands to close velocity or torque loops directly at the machine.

The power stage supplies a continuous load current of 5 A, providing a sustained ±5 A operating range when the bus voltage is at ±170 V. For acceleration or disturbance rejection, it can source or sink a peak current of 10 A for brief intervals. A switching section clocked at 25 kHz uses pulse-width modulation to control the output, while the H-bridge presents only 0.4 Ω of resistance to keep conduction losses low. Small-signal performance includes a 3 kHz current-loop bandwidth and a 200 Hz voltage-loop bandwidth, giving the drive control over rapid torque transients and slower bus-regulation tasks. Command inputs recognize a 2.5 V logic threshold, and the reference port withstands signals up to ±20 V with a 100 kΩ input impedance. For diagnostics, the voltage monitor scales the output voltage by a factor of 20 for measurement with standard test equipment.

Protective circuitry limits operation when supply or temperature conditions exceed safe margins. The amplifier shuts down if the DC bus rises above 185 V or falls below 22 V, isolating the load from abnormal voltage levels. Thermal monitoring disables the output when the heat sink reaches 70 °C. A 50 ms self-reset interval allows the drive stages to resume operation after the fault condition clears. This reset behavior reduces unnecessary downtime after a brief voltage or temperature event while preventing immediate reactivation during an active fault.