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Hi, While testing polarity check on transformer ct and the battery applied to the primary, a dangerous voltage and arcing may be generated while disconnecting the battery from the transformer winding. This happened to a very experienced technician last week. I just want to be sure that i...

Hello We have several outside control cables and ct cables that were damaged by small animals. They are too long to simply replace them all. What are your procedures and criteria to fix these cables? I would like to fix them with heat shrink or 3M tape and perform a megger if the outer sheath...

Hi, The Tripping and closing coil are feeded by the battery at 125 Vdc. Do you know how many amperes and how much times is needed to open and close the breaker? I check the manual but didn't see the answer. Thanks

Hi, we have an outside 125 V DC pannelboard with CSA certification with a lot of rust. We would apply a coat of paint mainly to improve its aesthetics, but some questions arose. Are we losing the CSA certification and is that there is a standard that can direct us in the method to use? Thanks

We dismantle high voltage old oil current transformers. When we remove the oil, there is often sand or something similar in the oil. Is this really sand? To send to the decontamination, we must indicate the type of material and we are not sure. Thanks and happy holidays

Hi, Would you accept this cable (see attach file)? Is there a standard on which we can rely to determine whether a damaged cable is acceptable or not, like one with the stranding a little bit open...

Hi, We have a Westinghouse 200 amperes 600 volts safety switch with 200 amperes class R fuse. We do some modification on our distribution system, so a other safety switch will be installed upstream with the same fuse, but we want to keep the first safety switch for a disconnection point and to...

Hi, To achieve a 12 pulses drive on a 600 volts systems, we have an isolation transformer with two secondary, one wye and one delta. There's one drive (ASC800 from ABB) on each secondary We plan to ground solidly the neutral of the wye winding (the primary is also a wye with the neutral...

Hello, We have a 69 kV system. the critical impulse flashover for our suspension insulator is 385 kV minimum. Normally, the supension insulator are installed phase-earth, with a cold and hot end. We have to install some phase-phase, what will be the impulse flashover for these? From what i...

Hi, I try to understand what's the difference between a C800 and a 10L800 CT. From what i understand, it's pretty much the same thing, considering 10% error on the C class. I think the L class is from an old standard, ASA (american standard association), and the C class from a new standard...

Hello, We want to use flexible power cable (locomotive cable) which have approximately 550 stranded for a 4/0. We have 2 choices for the quick connect connector (posi-lok from cooper), crimp or double set screw. Do you have any experience wich one is better for a flexible cable, to crimp or...

Hi, We have a 69 kV isolated neutral station. There is two 69 kV transmission line that are ending at the station. One of them is very old and many fault occur. These fault are not always seen by protection because the system is unearthed and the line is quite long for 69 kV. We have to...

Hi, We have a transformer delta-delta configuration with differential protection. The CT on the secondary side of the transformer are in the delta of the transformer, so the current measured isn't the same as the line current. I've made a sketch if it's not clear. So i want to know to do...

Hello, I'm looking for a chart with the maximum distance between 2 pole for neutral supported cable (aerial quadruplex NS75), 3 phase in aluminium + neutral ACSR , 600 volts. The cond. size is #6 AWG. A lineman told me approximately 160 ft, but i would like a good reference about it. Thanks

Hi, We have a place with a lot of MCCB Westinghouse type F and FB and some Cutler-Hammer type FD and FDB. The capacity of these breaker are 14 or 18 kA, but the short-cicuit current is way over. The breakers are in serie with a current limiting fuse, type RK-5. I have found serie rating...

Hi, At this moment, we ask for short-circuit current often to utility for arc flash study. Utility have study this problem for long time and went with a solution, but a very conservative solution. For MV, they say the short circuit current can vary from 0.5 to 12 kA. When you ask it for...

Hi, I've remark that on a lot of small hydro generator (4-5 MW), there's a little 3 phases capacitor just at the output of the generator, in the junction box, where the cables from the switchgear are connected. There is also surge arrestor connected in parralel at this location. My question...

Hi, I looking for a IEEE standard with recommended spacing between phase and ground in a switchgear (metal clad and metal enclosed), for MV voltage 125 kV bil. I search but didn't find what i need. Do you have some idea? Thanks

Hi, We were testing low Voltage CB with digitrip 520 M trip unit. The short time delay setting is .5 sec, but when we test it with primary injection, the tripping delay is 60 ms. The flag really show ST trip, not inst. When we test the inst., the delay was 50 ms. All the 3 breaker tested...

Hi, I'm looking for standard for the grounding of fuel tank and pipe. The tank are quite big, like in a refinery. I'm used to substation grounding, but since there's no ground fault current for a tank IEEE 80 cannot really apply. I know that you must have continuity with other part of the...