Need Help!- 3T-D won't energize hydraulic pump relay

[Jim Shaper]

I'll give ya the full scoop so there's total clarity as to what could possibly have happened.

I purchased a 1983 Nakamura TMC 3 about 2 months ago with no 3ph power here. Having sold my 10hp RPC (which I built) and converting all my three phase machines to vfd's, I'm completely sold on their merits, so I figured I'd run the new turning center off a vfd as well - using the 25kVA universal transformer as a form of choke. Having numerous problems getting the vfd to accept the transformer as an acceptable load, it finally fired up, but I didn't realize that it saw the transformer much as a locked rotor and had boosted the voltage accordingly. When I had realized what happened, I had already been running the machine on what was damn near 400v.

I opened the cpu cabinet to find some smoke, and the hydraulic pump hasn't run since.

My solution to producing the 24hp or so of 3ph, was to buy a 40hp motor and run that off the vfd to turn an 18KW 3ph generator head. So now I have 208v wye 3ph, but I don't have a machine that will function.

When the machine shut down after the only time the hydraulic pump has run for me, it was due to the vfd exceeding 50A on the output (a setting I had put in place to prevent over current). What I think happened was that the RF choke on the pump motor had failed and one of the legs was drawing too much load. It wasn't the machine that shut down. I had been seeing over heat or over voltage lights on the spindle drive board (it was the center led), but the machine was under an error condition and only the cpu would boot. That's the situation I'm in right now.

I do realize that due to the higher voltage, there was more wattage applied to the circuits than what they should've been protected from with the fuses. No fuses were blown.

So right now the coolant pump will function (manually switched from the front panel), and that relay should be fed off the same 24vdc power supply that the hydraulic pump is. I've bench tested the contactor and overload for the hydraulic pump, and I've removed the toasted choke from the circuit, but there's no voltage applied to the contactor (or the ground path is fried, but I haven't verified that yet).

I'm certain there's power to the pump contactor, as it's all fed off the same breaker for those other motor contactors (the working coolant pump, etc).

Right now I'm thinking it might be the board that issues the command to trip the relay to close the contactor when the machine is happy at initialization, but I'm not reading the schematic right to see which board handles that function. I do have all the manuals and schematics for the machine. None of the fuses are blown that I've found, and I'll be verifying the various transformers and power supplies are functioning correctly this afternoon.

What has me baffled is that there's no indication of damage anywhere else (no burnt diodes, no bulged caps). The error display doesn't indicate any codes. It's only the "machine error" light on the front panel, but the cpu will boot up just fine - except nothing works (but the manual coolant switch). I've even checked a number of the ice cube relays and none of them ohms out of range.

Sorry for the epic first post, but I'm at a loss to what to check next if it turns out there's no voltage going to the relay board from the cpu to energize the contactor coil.

Any help would be greatly appreciated.

[cncdiag]

Do you have any alarm Leds on your servo drives or spindle drive?
The machine alarm may be stopping the hydraulic pump from starting.
Has this machine run for you before?
Is there a seperate machine on push button?

[Jim Shaper]

Currently the only alarm is the one on the front panel that states machine error. Previously, the center led on the spindle drive was lit which is either overheated board or over voltage (more likely).

A friend of mine suggested going through a routine at start up to clear all the errors, and I think that's what I did originally that got it to fire under the over voltage condition (been a couple months now and I don't remember).

With any luck, it's simply storing an old error and not allowing the pump to initialize because of that.

The power up sequence is engaging the master breaker which feeds power to the single phase transformers and then you push the green on button to boot the controller and initialize the drives.

I did check and verify that the signal isn't coming from the icecube relay to turn on the contactor. I haven't reinstalled the pump's contactor yet (I did pull it and bench test it and opened up the overload to verify that's not damaged), or I'd have already tried the code clearing procedure. I should get that done tonight. With any luck, it'll be happy now and fire up.

What gets me flustered is that the contactor directly next to the hydraulic pump circuit functions perfectly.

[cncdiag]

Have you checked the DC voltages on the spindle drive. The test points are next to the black heatsink

[Jim Shaper]

No, that's actually on my list of things to do. I never got around to checking the power supplies outputs either, as I got further into checking the contactor out. But, there's no error lights on the control anymore, and there have been since the over voltage situation, and I also got the phase rotation error when I was playing with the rotation of the 3ph generator. I don't believe the drive is damaged.

I'm under the impression that what took the brunt of the abuse was the regulated power supplies. The fact that they are so heavily regulated is what shielded the boards from taking a hit directly. I had noticed prior to the shutdown (the one time the machine was initializing) that the choke on the hydro pump relay was warm, but after that it sparked like an explosion and fused two of the contacts shut (which has since been rectified). That was caused by manually engaging the contactor when the choke had probably already failed.

There's at least 3 internal transformers, and 6 power supplies within the machine that I'm aware of. I will go through and verify voltages (just to be sure they're all within range), but I'm not convinced that they're to blame right now.

The most logical conclusion to the current state of the machine is that it's indeed holding an error in memory and failing to attempt to energize the hydro pump's relay. With the OV error on the spindle drive, there's no way the drive would've attempted to run the spindle, so I don't think the excessive bus voltage ever made it past the IGBT's (or whatever diode's they used in the bridge).

[cncdiag]

If the power supply on the spindle drive is bad or is not getting voltage you will not get an alarm on the spindle drive. The spindle drive has a relay that will energize if the drive has no alarms. The contacts for this relay are normally part of the estop string and will stop the hydraulic pump contact from energizing. Do you have a wiring diagram?

[Jim Shaper]

The spindle drive board still indicates errors. That's what I was intending to convey when I mentioned it will throw an error light if I run the generator backwards - the phase error light will come on. It doesn't presently have any errors, so I don't see why it shouldn't be functioning.

However, the cpu won't fire anything up if there's no hydraulic pressure. Rather than simply bypassing the ice cube and running the contactor off the 120v transformer (which would enable the pump whenever the machine had power - which is pretty much what the damn thing wants anyway), I'd like to resolve the problem causing the cpu to fail to turn it on.

I didn't get to touch the machine at all today, so unfortunately there's nothing to report. Between the wife's honey-do's (I've been delaying over a month) and some customer work, it might be thursday before I get that contactor back in it and see what happens when I do the reset.

[cncdiag]

What is diagnostic 101 bit 4 ?

[Jim Shaper]

It's a 1. The whole string is 10110101.

I reinstalled the contactor tonight and tried the P and Can at the same time as hitting the green button and it's still pulling up with the machine error (I didn't wait for it to fully boot, so perhaps that's an issue?). I'm certain that's not the method I used before (fingers don't reach, so I would've remembered that one), but I haven't tried anything else. Pretty much just ran past the machine and did the diagnostics code and the other method.

If it rains here like they promise tomorrow, I'll probably get more time on the machine to check voltages, etc.

[Jim Shaper]

This is kinda out of left field, but is it possible I fried the 120v lubrication pump?

The way lube is up to the line, but in looking at the manual tonight it's saying the lube level could be cause for the machine alarm.

[Jim Shaper]

Curiosity got the best of me and low and behold, the 5v dc side of the power supply is out! (yes, I checked the fuse weeks ago - but I never put a meter to the contacts) That's actually opposite the side I thought had the choke get hot on, but it's the correct quadrant of the cabinet.

I'll be taking a bunch of pics for keeping wires straight when it all goes back together and the whole brick will be coming out for a look-see on the bench. I've got a feeling it smoked the diodes in the bridge, and if that's the case I'm looking at 20 bucks and we'll be back in business.

I also manually tripped the hydraulic pump contactor and the arcing is hardly visible (much improved from the virtual explosion that happened last time). I'll probably leave that choke out as there's no real reason to have it there. The arc happens before the cpu boots, and shouldn't ever be cut out till after the cpu is shut down.

[Jim Shaper]

I must not have gotten through the oxides on the screws when I tested the PS in the cabinet. Plugged it into the bench and it was perfect. Put it back in the cabinet and again, it's within .01v on the low pole at the cpu (dead nuts 5v on the other).

No change in status.