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Power PMAC & ACC24E2A


KennNova
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Having a problem with a pPMAC CPU and an ACC24E2A card. The ACC24 card powers up, but as soon as we try to enable an axis, the ACC24 shuts down...no lights. After a number on power cycles, and what appears to be blind luck, the ACC24 will survive an Enable command, after which it runs perfectly. The hardware is December 2011 vintage. End user mothballed the project for a year, so the system is in startup....has never run production. We updated the firmware in December 2012 when the project started back up. Rack has CPU, ACC24(1), DIO(1) and a 24DC power supply. We're using 2 sockets of Modbus. Any ideas?

 

Our IDE rev is 1.5.0.21 and CPU Firmware is 1.5.3.0

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The ACC-24E2A has an interlock circuit monitoring its supply voltages. If a supply is lost or dips below a threshold, power is dropped out to the output op-amps, and the "power good" LED is turned off. The primary intent of this circuit is to prevent the outputs from pulling to one rail when the opposite supply is lost (obviously a very dangerous possibility). It also can indicate an overloaded supply.

 

Do you still trip on enabling when it is disconnected from the drive?

Can you see a dip in the supply voltage(s) when enabling?

Does your drive draw significant supply current through the ACC-24E2A when enabled?

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The amp is a Copley Xenus rated at 6 amps driving a Parker linear motor rated at 3.8 amps. (Numbers are from memory, close but not exact.) I'll check with Copely to see if they have a start-up current spike. The drive is fed from 230, 3 phase while the pPMAC derives power from a 24 VDC power supply. We'll verify the level of the 24 VDC supply. We'll also monitor with a scope during an enable event.

 

I don't understand your last question. There is no direct connection between the ACC24 and the drive except the command signal and the buffered encoder repeater. Are you talking about the input impedance of the Copley reference circuit? We are limiting the DAC to arround 18000 so that the motor is not subjected to over drive.

 

Also, once we get the drive to enable, after being shut down for the night, we can enable and disable the drive all day long with no problem. We have only seen this on a cold boot after an extended (overnight) shutdown.

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The power supply feed the UMAC rack was 24.2 volts from moment of power up. Are there easy places to measure the voltages produced by the power supply in the rack?

 

This morning, the card stopped responding all together. The motor vibrated and would not tune. The CPU is reporting i²t faults. The motor runs fine from the drive. We installed a spare card from our development system and it performed as expected. We will swap the original back as a test, but first we will try a cold restart tomorrow morning. During all of this, the supply voltage to the UMAC rack was a good 24.2 volts.

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