big denford triac problems

[Chaz]

odd thing is the guy i bought it off had ran it for 11 years with no problems with this set up,
now here's the thing, he disconnected the cabling from the phase convertor to facilitate moving the m/c and marked up all cables and where they go, i was very careful to re wire exactly as marked, but if he has made a mistake................

So I've had a quick look at every Denford wiring diagram I can see. I dont see anything where the actual servo drives are actually connected to all 3 phases, they seem to take a single phase for input power. That said, yours might be different.

[mark35gun]

you may well be right, i need to source boards before any testing can begin, although i don't know if i dare turn on the m/c!

[mark35gun]

heres a pic not very good i know
BTW the phase convertor is a boost electrical engineering one rated at 8 hp, which i know is miles to big for the denford but it came with it

[Chaz]

heres a pic not very good i know
BTW the phase convertor is a boost electrical engineering one rated at 8 hp, which i know is miles to big for the denford but it came with it

Very different looking to mine. Are you able to identify and take pics of the servo drives themselves? The wiring to them will be of interest, so too any model numbers to review how they get powered (based on a specsheet).

[mark35gun]

z axis no A06B-6058-H003
X,Y combined AO6B-6058-H221
i will post some pics in a short while

[m_c]

The reason I was asking about the phase converter, was they can produce voltage spikes, but if it has been working with the converter previously, it's not likely to a be problem. Just to be sure, it's probably worth measuring the voltages to make sure they are roughly similar.

Looking at the photo of the cabinet, it looks like the machine takes 3phase plus neutral (I'm assuming the blue wire between the main power switch, and main earth cable is a neutral..).
Again with the phase converter powered up, I would check the voltages. Check the 3 combinations of the phases, then each phase to neutral, then compare neutral to earth. Phase to phase should be similar, then phase to neutral should be similar, however the artificial phase (the one generated by the rotary) will likely be higher, but shouldn't be excessively higher.
On a normal 3P+N setup, neutral to earth should be near zero volts, however depending on the phase converter, it may be floating near normal single phase voltage.

[Chaz]

I looked up the drives, it looks like they take 3 phase (220V on the ones I saw) for the main power and a single phase feed for 'control voltage'.

[mark35gun]

no neutral on the m/c, the voltages across the 3 phases are 440,440,380, i am sure that the problem exists when the rotary phase converter is turned off without isolating the m/c first as it has done this twice now as soon as the motor shuts down the ammeter shows a current draw of +40 amps which lunches the control, normal running the ammeter shows 2-3 amps with the m/c on, i don't understand why there should be a large current draw when the phase converter is turned off and the m/c isolator is closed, i have no experience of rotary phase converters so i do not know if this behaviour is normal or not

[m_c]

no neutral on the m/c, the voltages across the 3 phases are 440,440,380, i am sure that the problem exists when the rotary phase converter is turned off without isolating the m/c first as it has done this twice now as soon as the motor shuts down the ammeter shows a current draw of +40 amps which lunches the control, normal running the ammeter shows 2-3 amps with the m/c on, i don't understand why there should be a large current draw when the phase converter is turned off and the m/c isolator is closed, i have no experience of rotary phase converters so i do not know if this behaviour is normal or not

Any chance you could take a photo of the inside of the phase converter?
When you say you switch of the phase converter, how do you switch it off?

My suspicion is switching off the phase converter doesn't actually isolates it's output, so it's still outputting 2 phases at full voltage, along with leaving the balancing capacitors active (aka acting like a static phase converter), which when combined with a switch mode load (aka the FANUC power module), could be resulting in some very high voltages on the false phase.

[mark35gun]

yes i will take some shortly, i think you are right, just stopping the phase converter with the stop start control Ie stop button, which is fine as long as you know to isolate before stopping.
i have always used vfd inverters where required but never rotary types, i was on the understanding that the rotary types were ok for non electronic machines, but too "coarse" for sensitive equipment, in saying that this m/c has run with this setup for many years so should it be considered ok?