Recent content by hec64

By looking at the picture it is EMT conduit with flex conduit close to the panels and any tight bends. Or is it GRS? Are there more than 4 bends per run? Do you have a high resolution picture we can see? Very interesting....

Does anyone in California using the ABB AMVAC? I have seen other thread that have indicated it is different way of thinking process http://www.eng-tips.com/viewthread.cfm?qid=136356 http://www.eng-tips.com/viewthread.cfm?qid=133558 If it does not have a trip coil, then how do design your...

David: I want to apologize for the misunderstanding. It is as Jghrist is describing. The conduit tag is the same between manholes, but changes when it leave the manhole or does not have any tag in the manholes.The problem arises on the fact that previous contracts the engineers used one...

We have a discussion on how to tag high voltage conduit. We are doing a new installation of conduit for 4160 volts. We are putting several manholes and one of our engineers, who is doing the design, is assigning conduit tags from manhole to manhole and all the conduit tags are different for one...

Thanks everybody for your response. Lionhutz, you are right, the field current is not the problem. The problem is that the MOVs are blowing up, because during start up the motor is under load.We will change the MOV to a larger size. We cannot put back the ball valve. That will be more costly...

You need to get a structural engineer to do this for you.

Does anyone knows where can I get information regarding how the synchronous motors starters works? We have a 700 HP, 2300 volts synchronous motor connected to a water pump. We used to have a ball valve to open the valve after the motor started. A mechanical engineer came and remove the ball...

My company installed three 1000 HP Worthington Pumps (ductile iron) in 1991. Ten years later we found that the pumps casing were corroded like the pumps were cavitating. We know the pumps were running within their curve limits and we know that this was not possible. We though it was a corrosion...

This is a VFD but we did not want to get the signal from the VFD. We want a direct connection to the motor itself.

I am trying to get a speed feedback from a 1 HP AC motor using a simple tachometer. I have look around but the only one I found is one that Dart Controls sells. The device is very simple. It attaches to the end of the motor and give pulses. (the model number is PU-2E for a single pulse per...

For your information Siemens bought Robicon. So I do not think Siemens has large VFD units. Now in regard to harmonics, my company bought two 4160 volts, 1000HP Perfect Harmonics units and I went to the factory to see the test. When we were testing the unit the THD were more than 5% and I asked...

I have tested 1500 HP vertical motors using IEEE 112, method F, but the IEEE also assume values to calculate an equivalent circuit, so the stray losses are still a calculated value. Make sure you can measure the speed of the motor accurately. By using the IEEE moethod B, (Dynamometer) all the...

I appreciate very much your comments. ///Was this design based on appropriate engineering calculations adhering to any industry standards?\\ My engineer did his design based on assumptions that were not correct. We accept that responsibility. We are implementing new guidelines that will avoid...

I understand how to get to 5 ohm ground resistance, but do we need to get to 5 ohms?

One my engineers design a valve control house. This buildign has three rooms: the lectrical room the generator room and the valve control room. The electrical service is at 2400 volt, 3 phase, 3 wire wih a 45 kVA transformer and we install a pad monted transfromer inside the electrical room to...