FAQ: What are potential implications of using an Electro-Mechanical Relay or Switching Power Supply in conjunction with a Sigma II Servo System to enable the motor? Can A.C9 and A.E2 alarms be symptoms?
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Sigma II Servo Systems (SGDH amplifier) require a 24VDC input to enable the motor. It has been observed that in many cases, an Electro- Mechanical Relay or Contactor is utilized as a Master Control Relay to feed this 24VDC signal to the amplifier and perhaps turn on other devices in the control panel at the same time.
In some cases, an A.C9 (Encoder Communications) alarm occurs as soon as the relay is engaged. Assuming the wiring for the encoder and grounding of the amplifier have been done properly, the cause is noise generated from the Electro-Mechanical Relay.
Here are some remedies:
1) When using a DC relay, install a "fly wheel diode" across the relay coil. When using an AC relay (or contactor,) use a surge suppression device. This will reduce the potential for chattering, which in turn damps the noise.
2) Mount the relay as far as possible from the Servo Amplifier in the panel.
3) Route encoder cables away from the relay.
4) Install a ferrite core (Yaskawa #ESD-SR25) at the SGDH end of the encoder cable in the panel.
5) Consider using a Solid State switching device instead of an Electro-Mechanical one.
If an MP940 is used in conjunction with Sigma II amplifier, an A.E2 alarm may occur. Assuming the cause is not MP940 processor time-out or MP940-SGDH synchronization error, the cause can be noise generated from the Electro-Mechanical relays. The same remedies mentioned above should prove helpful.
Switching Power Supplies are also noise-generating devices that could potentially cause an A.C9 (Encoder Communications) alarm.
Here are some remedies:
1) Mount the power supply as far as possible from servo amplifier.
2) Route encoder cables away from the power supply.
3) Install a ferrite core (Yaskawa #ESD-SR25) at the SGDH side of the encoder cable.
4) Consider using a linear power supply instead of a switching model.
Keywords: Error, AC9, AE2
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