Identify schematic symbol

Cayce1109

I'm trying to diagnose a voltage issue on a machine I'm working with. In the schematic, 480v current goes through the K120 contactor, into -L001, and comes out as 960v and into the G100. The manufacture claims that -L001 is NOT a transformer and is "just a line filter" and wants me to replace G100 which is a $9000 part. They claim I am getting feedback from G100 causing me to get the voltage spike, even though I measure voltage with the wires disconnected from G100. From what I can find, U/V/W1 and U/V/W2 are drawn in as inductors and with 3 of them next to each other in close proximity, it should be a transformer. Please correct me if I am wrong, as I've been working on this machine for 2 weeks fixing problem after problem. I've attached the schematic as well as the large object in question for reference.

ceptimus

It looks, to me, like a "3-phase line reactor", otherwise known as a "3-phase choke", or "Line choke inductor". It's similar to a 3-phase transformer but only has primary windings - no secondaries.

It's a current-limiting device which also filters out spikes. If you search for those names I gave above, you will find pictures, and suppliers that will sell you an equivalent component. You have to specify the working voltage, current, and either the reactance, L, in henrys, or the AC impedance in ohms. You can convert reactance to impedance by multiplying by 2 x Pi x f, where f is the frequency of the supply.

There's not much to go wrong with a 3-phase choke, so providing it looks intact, the contacts are tight, and you can't see or smell any burning, then it's unlikely to be the cause of the fault.

You should check the resistance (with the supply disconnected, of course) of each phase with a multimeter, measuring from L1 to L1.1, and similarly for L2 to L2.1 and L3 to L3.1. Your multimeter will measure the DC resistance, which should be very low - and the readings for each phase should be about the same.

Cayce1109

ceptimus wrote: »

You should check the resistance (with the supply disconnected, of course) of each phase with a multimeter, measuring from L1 to L1.1, and similarly for L2 to L2.1 and L3 to L3.1. Your multimeter will measure the DC resistance, which should be very low - and the readings for each phase should be about the same.

Got very low resistance on each line, and everything is snug. I just don't understand how the G100 can cause a voltage spike that big. Guess I'll have to replace it. I appreciate the clarification!

kwinn

According to the schematic L001 is a set of 3 inductors that are used as filters, and that is a reasonable conclusion. If the inductor has a break or crack in the wire or insulation, or a poor connection somewhere that may account for the high voltage reading. You could switch the V2 and W2 wires to see if the problem moves to V2 or remains on W2. You could also pull the entire assembly out for a visual inspection, and it may even be possible to have the coil rewound if that turns out to be the problem.

frank freedman

Take a megger between the PE and each winding to see if the insulation is good for each of the windings. But if the MFR is saying the G100 may be the fault, they may be right. Do they offer a return with possibly a restocking fee if the part does not solve the problem?

Dumped the WAG.

DigitalBob

I'm guessing thats a GE overcurrent relay? Those inductors are line reactors to keep the noise out. Is this a new installation or a machine that has been running for years?. What kind of machine is it? I know with large VFD drives the type of cable you run from the VFD to the motor is very important. It needs to be the fine strand welding type cable not THHN.

frank freedman

Is this part of a system using Sigmatek controllers? Two weeks fixing lots of problems... Did this thing take a power hit?

How were you measuring 960V? That is the P-P value of 480RMS. Looks like the input of the G100 may be a 3 phase rectifier. Could be a part failure there, though you did mention that your measurements were with the G100 disconnected.

Pardon the curiosity / kibitzing, frustrating equipment problems to you, interesting puzzle to me. Good luck, let us know what the answer was if you get time. Thx.