The maximum bridge temp is 95C, so no 60 is not too hot. The motors and drives are bothe oversized in order to provide overload capacity. The load has not changed, and neither has the current required. These drives are for a grate clinker cooler, and a cement kiln. There are identical drives...
I agree that 60C is not out of bounds. My concern stems from the fact that these drives historically stayed below 30C for years. Voltage and current appear normal on the line side of the isolation transformer, on the drive side is where I took the stange readings posted. I'm assuming that there...
2 different drives are experiencing higher than normal bridge temps after a 6 month shutdown. Both are ABB DCS 500's. One is for a 40 hp motor, the other is for 2 75hp with the armatures in series. They are both way under FLA. Before the shutdown these drives both had bridge temps under 30C...
A kiln can over run once they have unbalanced rings built up also. I haven't had the chance to work with a modern AC kiln drive yet, just dual motor DC drives.
Can you push in the moveable contacts by hand? I like to check contactors by hand to make sure that nothings binding up. Is it possible that the 120V coil is DC. A lot of bigger contactors use DC coils, and have rectifier and economizing module built in. The economizing module allows for full...
The field is applied at 95.5% of sync speed. The mills are started up loaded, and the motor is brought up to speed using a softstart. Historically the mills were ground out before shutdown, but now they are taken down loaded.
The GE field breakers are looking real good. I'm waiting for a price for the Telemecanique option so we can compare them with the old GE's. They look like really nice contactors.
The confusing thing is that all 5 field breakers that have no overlap were on their last leg. The one with the 3 ohm resistor had the NC pole damaged, and the other 4 had the NO poles dam
aged. The field breaker that exploded and took out the exciter was not the one that had the miswired...
I didn't think about the SCR's having any affect on the current. We don't change the gating on the SCR's at startup or shutdown, we just allow field voltage to float while the motor is down. Even with the SCR's, wouldn't the L/R cause troubles with the contactor, if there was no overlap of the...
Well, it was broke. We have 5 of these motors that were updated about 6 yrs ago with new contactors that had no overlap. All of these contactors are in very bad shape, and one has exploded and taken an expensive exciter with it. Contact maintenance is not the concern, because the contacts...
I took more measurements on both motors Friday. Both field discharge resistor circuits measured about 57A through 33.4 ohms. This gives me 1903V. If this is the case, why can't I test the insulation resistance over 500V?
I have installed the original breakers on both of these motors, and the discharge resistor is wired in properly. I'm just trying to make sense of the different readings. The motor that reads 3A had the discharge resistor hooked up wrong for the last 6 yrs 3 ohms instead of 33.
I'm checking the...
Finished installing the new contactor today and still have some interesting readings. I can't figure out what the value of AC induced voltage from the field is during startup. I measure 3A on this motor, and on an identical setup 55A. We checked the field with a megger, and thought that the...
I'm pretty sure that AB doesn't make one, and there are very few that have the overlap of the contacts. I found one in an obscure ABB catalog, and had trouble getting any information other than made in France. The one that was just installed, is actually a new in box contactor made by GE...
I'm working with 2 different motors, and I'm trying to interpret some basic test results. I have 2 1250hp 4160V 40 pole sync motors, Field is 250V 66A and the field discharge resistor is 33.4 ohms. The Field is supplied by an SCR rectifier thats mounted in the substatation by the starter. The...
The abb rep I spoke told me that all of there bar contactors are made in France. That's where I'm waiting on the quote from. As far as maintenance, the enclosures are kept clean, whatever your seeing must have been from the fire.
Recieved a quote for a GE contactor today. Pricey, but not nearly as much as another failure. All of our Field contactors look terrible, and it's only a matter of time before the next problem. Good thing nobody had the cabinet open at start up. I'm waiting for ABB, and would like to compare...
