Electrical multimeter

Fabrik8 said:
Some of the home energy monitoring products might be a good fit, depending on what you need for sample rate

Curb, Eyedro, Neurio are all worth looking into. They come with current transformers and they all have internet connectivity by default (because smartphone apps and remote management rule the world). Most are meant to be installed directly into a breaker box, etc.
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This is the answer if your budget is at least $100. One of the home energy monitors with ct clamps.
 
awheelterd said:
@Lurch830 I'm in Johnston County, between Clayton and Wilson on 42. I haven't been at NC State since 2011, maybe I should update that lol! I appreciate the offer! This isn't something that I need for an ongoing issue moreso just another tool to make troubleshooting easier.
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10-4, if you (or anyone else) needs something like this in the future you want to check with your electric provider as IOUs, most co-ops & some municipals have a 3 phase data recorder they'll loan out/set-up to help diagnose issues. The company I work for serves 92 municipals across NC, SC & VA (Clayton & Wilson are 2 of our members along with the other 3 I mentioned) and we have 2 to assist those that don't own one. Last time I used ours was in Edenton to diagnose why an elevator kept tripping the breaker and the elevator company blamed the incoming power. Left the recorder on the main feed for one week, on the elevator circuit the next & a nearby coffee shop the next. Elevator company finally sent a tech out and fixed their problem after seeing the graphs.
 
FWIW I have quite a few (expensive) meters, and one of my favorite meters to use still is my Blue Sea Systems meter. It’s a very robust meter that can read high ampacity DC (not a common feature) for a reasonable price.

The best residential or commercial monitoring system I’ve come across is eGauge. Their platform is incredible.
 
The issue I have been having this week is that I keep blowing the same 45 amp fuse. 3ph 480v, 3-45amp fuses feeding a contactor for a blower. FLA on the blower is 35 amps. I have the overload for that blower set right at 35. I only trip the overload when I lose a leg when that one fuse blows. With the overload being set 10amps below the fuse size, it should never be touching the fuse. Fuses are slow blow, I have accidentally bought quick blows before and would pop the on startup inrush. Learned my lesson on that one. I have the drive on the feeder supplying product to the blower turned down to 43hz so I am only pulling 30amps on any leg. I still keep popping fuses. I have checked amp draw above and below the leg/fuse in question and it is exactly the same as below it and below the contactor/overload. But the one A leg fuse still blows randomly. Im thinking the fuse block itself is bad now. (Bussman 600v 60a block). I can't shut the whole plant down right now to change the fuse block so I have bypassed it on the A phase and am now just riding the overload (don't bother asking how I did that :lol:) Anyone have any other ideas? Also, just to be clear, I am not blowing fuses in the B or C phase only A.
 
We had a similar issue in one of our cabinets. Kept tripping out one of the legs. Spent a few days working on it. Pulled everything apart and found out the breaker in the control cabinet had shorted out internally that we couldn’t visibly see without pulling it off and looking at the back side.
 
rockcity said:
We had a similar issue in one of our cabinets. Kept tripping out one of the legs. Spent a few days working on it. Pulled everything apart and found out the breaker in the control cabinet had shorted out internally that we couldn’t visibly see without pulling it off and looking at the back side.
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Yup, had something similar happen before. That's why I'm leaning towards the fuse block.
 
If it’s a motor circuit, make sure the fuses you use are motor rated. It may need time-delay fuses if it has a momentary surge above 35A for a split-second
 
336wheeler said:
If it’s a motor circuit, make sure the fuses you use are motor rated. It may need time-delay fuses if it has a momentary surge above 35A for a split-second
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Yeah they are motor rated. It doesn't pop on inrush. Just randomly while running. Thinking the fuse block is the problem now.
 
What vfd are you using? If it's anything decent you should be able to read and monitor your current output on each leg. You could test the fuse block by switching two legs (top and bottom). If same fuse blows then it definitely looking suspect.
 
braxton357 said:
What vfd are you using? If it's anything decent you should be able to read and monitor your current output on each leg. You could test the fuse block by switching two legs (top and bottom). If same fuse blows then it definitely looking suspect.
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Vfd is on a rotary vane airlock, not on the blower. The blower is just on a regular ol' starter since it is only turned on once or twice a day. After I bypassed that one fuse this AM it has ran trouble free all day. I've checked it loaded and unloaded several times and amps looked good every time. I have a new fuse block to slap in there Friday.
 
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