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I am running a motor starting by ETAP voltage control module. I set current limiting at 350%FLA and initial voltage setting was set at 55% to ramp to 90%. I was expecting to cause voltage drop on the bus within 15%. But actual voltage drop on the bus was about 30%. I am wondering if I set the...

I am working on 400V system. 4 wire system is required for the incoming section. so the 4 pole circuit breaker is needed for the main incomers. IEC also recommends that 4 pole circuit breakers shpould be used if SWGR or MCC feeds equipment in a hazardous area. But I am not sure about the...

I am working on International project based on IEC standards. But I don't have data for tripping times of Current limiting circuit breakers and fuses. Some people said it is 1/2 cycle. Other people said it is 1/4 cycle. I would apprecite it if anybody here can provide me more acurate infomation.

I have a Russian Collegue. He told me that Paper insulated cable is still common in Russa. I got confued by him. To my knowledge, paper insulated cable should be used on higher voltage level. below 10kV, we should use XLPE. is there anybody from Russa?

I am currently working in a Russsian project. As per Russian Code PUE. Power cables larger than 3x16mm2 should be with at least 1 diameter spacings in a cable structure. Based on this, there would be a huge amount of cable trays. Some of my collegues are saying that cable tray is same as cable...

I did some study regarding the possibility of using fuse -contactor scheme for 10kV motor. I have noticed that there are no large rating fuses which can suit large motor application. The max. 12kV fuse for motor protection is rated 200A. Apparently it is not good for some larger motors as shown...

We are working on a russian project. I am trying to find the grouping factor for 1 core cables and 3 core cables. My understanding is that the grouping factor for 1 core cable and 3 core cables are different because of diffenrent structures of cables. We have the goruping factors from a...

I am wondering if power factor correction has any effect on power stability?

I am working on an international project. One of our engineers insists on using 12kV contactor instead of breaker. There are a couple of manufacturers available for 12kV contactor, such as ABB, Siemens, and Areva. I am not feeling comfortable with using 12kV contactors. My concern is as...

Hi, Fellows, I am working on a project on which I have to calculate actual cable ampacity in order to decide overlaod setting of the cable. But I am not sure about the normal temperature rise inside MV SWGR. Does it affect cable ampacity if the cable is run partly inside SWGR? Based on CEC, if...

We did some testing on the ground rod system in one of our stations. The test results are extremely high. It was 1800 ou with one rod. It was 200 ou with 8 rods and bullding steel structure. I think it is due to a poor design. We are thinking of reducing the soil resistivity by injecting some...

I have a question regarding SR750. Can we edit Setpoint group 2 on Enervista software?

I just started arc flash study recently and I'm not familiar with IEEE1584. Does the catgory have anything to do with relay setting level. In our case, arc flash levels are Cat. 0,1,2. I don't think we should worry about the arc-energy. But I don't know if there are any standards about this...

I came across a project which I have to deal with a lot existing trnasformers. For those transformers, I have to find out their actual inrush current based on real short circuit capacity of the source. The higher the short circuit capacity, the higher the inrush current. I am wondering if...

I want to start a 5000HP motor andthe system is too weak. I thinking of using Auto-tranformer and softstarting methods to start it. But whenever I tried it by ETAP, it always caused the bus Voltage drop to exceed the requirements. Does anybody here have better solution for this system?

I am dealing with a ulitity company. I am doing a coordination settings for a pump station. Utility company is doing their own settings. They insist on using instantanneous settings for SEL587(Secondary of transformer). But their settings would make trip the whole pump station, which is not...

I am doing a coordination study for a ficility. I got a TCC curve from a Utility company.They set their Curve way below our main incomer curve. This a radial distribution sytem. A 5MVA transformer (69kV/4.16kV) is supplying power to a 4160V SWGR, which is a single power source.Secondary cable is...

I am doing motor startng study. I have two sets of data from motor manufacturer.One is motor circuit data, which is impedance data. The other is motor characteristic data, which is speed-torque curve. ETAP software accepts both. I am wondering which set of data is more accurate for the motor...

Hi,Guys, I am dealing with One medium voltage starter company.I don't want to mention its name. This company chose a fuse-contactor combination and our senior enginner approved it. But later on, after I did short circuit calculation, i realized that fuses can't well protect the contactors...

Hi, I have a tricky question. When we do the realy coordiantion, we always expect the protective device can operate at less than the minimum short circuit, like L-L faul. In my case, I am using an extremely inverse curve to protect against Minimum fault to max. fault, when the fault...