Sare 750 with A2100 tripping main breaker

[mgnbuk]

We have a Sabre 750 with A2100 control and Vickers drives that has started tripping the main circuit breaker in the input transformer box.

The machine may trip when the "Power On" button is pressed after the control boots up, or it may suddenly shut down after having referenced OK & been operational for a while. The spindle is stationary when this happens - the axes may be stationary or moving (jogging or referencing).

I have had the power supply out and it was filthy. This has been cleaned, but the fault remains the same. The power supply is a PSR4 with the soft start option. When the machine is powered up, all the drives (axes & spindle) & the PSU show green Leds - though on one of the axis drives (BDS4 6A - Y axis) has a dim red glow internally suggesting that an Led is on deep inside the drive ?

My feeling is that the PSU is at fault, as this appears from the schematics to be the device most likely to draw sufficient current to trip the 100A MCB & it does not have any other form of protection.

Has anyone come across a similar situation, or could offer advice ?

Thanks & regards,

Nigel Barraclough
Coidan Graphite Products

[mike_Kilroy]

i agree - most likely the psr4/5-275 power supply.

some of the bds4 drives have enc emulator optin card ibside - it has red leds on it - prob the glow u c.

[mgnbuk]

Thanks Mike,

I'll pull the power supply again & get it looked at.
I guess that will be another £1000+ repair !

Regards,

Nigel B.

[mgnbuk]

It has been a while since I posted this - time for an update.

The drive power supply was sent away to a specialist repairer, who could find not fault with it. When it was replaced in the machine, the same fault came up - after a couple of minutes powered up, the main circuit breaker tripped. When I tried again, however, the X axis drive showed an overcurrent fault rather than the circuit breaker tripping. I disconnected the X drive motor connections as suggested in the drive documentation & the machine stayed powered on with no overcurrent alarm on the X drive. A bit more checking with an insulation tester pointed the finger at the cable to the motor, not the motor itself.

When I eventually extracted the dragchain assembly and cables (whoever "designed" that arrangement should be shot !), I found a hole blown in the motor power cable
within the dragchain.

I have changed all the cables as a matter of course, replacing the basic, unscreened power cable with an IGUS dragchain rated screened cable (as shown in the BDS4 manual - could Cincinnati "designers" not read ?). While checking the cable specs. it became apparent why the cable had failed - the installed cable had a minimum bending radius of 110mm & it was installed in a dragchain with a bending radius of 55mm ! The cable I fitted has a bending radius of 82mm - far from ideal, but the smallest I could find & better than the OEM. Hopefully it will see me out !

Regards,

Nigel Barraclough

[mike_Kilroy]

good job! excellent feedback. thanks for sharing!