After getting this machine up and running we get an "over voltage" alarm #119. We loaded a test 3D program, to get the RS232 setup. 20 minutes into the program when it's cutting a very small section and the servos are really working hard and fast the machine rapids up and quits with a "overvoltage" alarm, and the servos turn off.
Also We tried turning up the feed in the program to see how this machine would run, and at about 160 inches a minute it started to shake and vibrate, is this as fast as this can be run? We thought we were going faster than the buffer could accept the program (we are connected @ 19200) But we slowed down the feed to 60 inches a minute and still get the error code. This machine has approx. 3500 hours on it, do the brush servos need to be cleaned

061006-1320 EST USA

SpringKing:

You did not say so, but I have to assume that you are operating in DNC, drip mode.

If you have a 1 meg memory and initially this is filled up from RS232 before you start machining, then you might run 20 minutes before you drain this memory. 19.2 kbaud is almost certainly not fast enough to keep up with machining short strokes. Most 1995 machines are limited to 38.4 kbaud, but that is better than 19.2. Newer machines starting around 1996 have 115.2 kbaud capability. If running in drip mode remove all un-necessary CNC programs.

You should use 7 data bits, even parity, and 1 stop bit.

If you have a lot of start stops of the servos, then regenerative braking may raise your DC voltage on the power supply capacitors an excessive amount. You may be able to reduce this problem by changing the transformer taps so that your steady state DC voltage is on the low limit side rather than the high side.

If you slow your feed rate so that you are never starved for data from RS232, then you may eliminate your over voltage condition. This will eliminate the constant start stops.

Over-voltage does not relate to carbon dust from the brushes, but yes it is important to keep the carbon dust cleaned out of the motors. HAAS has some specification like --- the shunt resistance from motor brushes to ground should not be less than 1 megohm. I am not sure what the exact specification is, but it is some high value.

Slowing feed rate is a means to reduce the data starvation problem.

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On a machine that age sometimes you can get the overvoltage alarm because the regen resistor is overheating. The quick and dirty solution to this is put a fan blowing past the regen resistor. We used a cheap bathroom ceiling fan and it worked fine.

I don't often question gar's advice but I think dropping your transformer taps to move the DC buss to the low limit is a bit dicey. This is not going to affect the regen braking but it could mean your DC voltage droops too far during servo acceleration. You should certainly check it to make sure you are not running near the top limit.

A check you should do is to make sure the regen resistor does not have an open circuit. It should be hot, if it is not getting hot it is not in the braking circuit and that will give you an overvoltage.

The vibration you are getting at high feed rates is related to the fact that 3D programs are normally kazillions of little straight moves. There is a setting which controls how the machine behaves at corners between straight moves. This is Setting 85 Max Corner Rounding; default value 0.025. You might check this because if it is set to 0 the control acts as if an exact stop is commanded in each motion block (to quote my manual). The actual setting when not 0 controls how much the control slows down at corners.

061006-1432 EST USA

Geof:

Your comment is a good one. Certainly cooling the regen resistor is a good first try. Does the over temperature give the same error code as overvoltage? I am not where I can look at a manual at the moment.

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061006-1432 EST USA

Geof:

Your comment is a good one. Certainly cooling the regen resistor is a good first try. Does the over temperature give the same error code as overvoltage? I am not where I can look at a manual at the moment.

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I am going from memory regarding overheating the regen resistor on our 1995 HL1; I think on more recent machines the alarms are separate. I also speculate that if your DC buss is running near the top limit a hot regen resistor could push it into overvoltage simply because the regen resistance has increased. But I also speculate it might be an open circuit in the regen resistor because servo braking does not really dump that much energy.

I had the same alarm coming up on our VF-1. It also came up with an over heat alarm at the same time usually. I just had the processor board replaced and now the alarms never come up.