Recent content by cjhut

To some a of the above questions, I did use as true RMS meter. In fact, I used two fluke true rms meters for both the voltage and amperage and got the same readings. I also did not notice a change in the voltage with the loading of this transformer. I haven't taken it down to no load, but I did...

When I gave the 277v reading to ground, I was pretty much saying that as a nominal voltage, It did vary a little from phase to phase, but just a volt or two. I was just trying to let everyone know that we have a properly grounded wye, with no floating ground.If it matters I can get some exact...

The 480volts/current readings were taken from the load sides of the soft starters. There is no voltage/current difference between the line and load side of the soft starts. Each motor has it's own feed coming from the switchboard-single conductors per phase in steel tray. No parallel conductors...

I took some readings on the primary side today and here's what I read volts A-B 2251, volts B-C 2270, volts C-A 2280. I watched it for a while and the voltage is never more than 30 volts difference across any of the phases. SOmetimes it is as little as 10volts. I cannot guarentee the phasing on...

I have a 3 phase 480v 2000a main lug only switchboard being fed from a wye secondary of a 1500KVA three phase oil filled transformer. The primary voltage is 2.3kv. There are three fusible disconnects on the switchboard feeding three soft starters each driving a three phase squirrel cage motor...

The magic words are exposed energized parts, which doesn't apply if all of you covers and barriers are in place.

We wanted to move an existing conduit for a 2300volt 250hp motor. The original conductors were 5kv nonshielded EPR insulation, in steel conduit in free air. We now want to move it underground in steel conduit. I called the local wire and cable distributor and it seems I have two options. There...

Are the capacitors individually fused? Are you blowing the main fuses? Is it the same one all of the time? Is the capacitor bank enclosed, outdoors? We have had birds, raccoons and cats step across our old 410kvar 23kv cap bank in our outdoor substaion. You should see what that does to a small...

Doesn't sound like a neat and workmanlike manner. I also may inhibit future maintenance.

Phovnanian/PetroSynergy--I agree with you both. I have left out alot of details about the water cooling system. We have discussed these types of options before. I would love to see a cooling tower sytem, but we don't have enough physical space left to install a unit big enough for the BTU's...

phovanian, A water problem turns into a bad connection in a hurry. If the water stops flowing the buss and connected cabling expands considerably, then when not loaded cools. This causes the connections to come loose. So heat is the enemy, which is the first problem leading to a bad connection.

Thanks Zogzog. I'll look into these. My only concern would be the magnetic field caused by the large currents. I will talk th=o the mfr.

We have a 7MVA electric arc furnace transformer that uses water cooled jacketed cables to feed our electrodes. Each phase has two paralled conductors connecting from the secondary bus 275v 17,000 amps to our electrode holders. At times we don't get enough water flow to one or both of the...

Check out www.dartcontrols.com. We use these for our fractional HP PM dc motors. Everything is built in to tune in overload protection etc. We use the model CM50 with a 10 or 5kohm (can't remember) $15.00 knob pot. These have been a very durable unit for us. I have about 15 in our plant and they...

Hello, I currently have a 2,300v 250hp squirrel cage motor being fed from an across the line starter. No VFD's- nothing fancy. My company wants me to reroute the motor feed, which is now in steel rigid conduit running across the building structure to the motor. They want me to take it...