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The IEE regs for LV portable equipment states 400ms maximum dissconect time. For the simple reason that it is less than the time span of a heart beat, if the heart is held in shock for a time greater than a heart beat it will most likely go into a cardiac arrest. Bit of hard luck if you have...

Hi Redox In the UK (and used around the world) the "standard" was BEBS12, this gives the standard for the wire numbering in LV - HV switchgear panels. However they never showed any examples so some manufacturers and designers interpretate the standards in diffrent ways. I have added a link to...

Have you got the setting software for your mlulilin relays? If not you can download them from here. http://www.geindustrial.com/multilin/software/index.htm When you are in the program for your relay, open a new file and go to page S2 (Settings). There you will find the relevant settings that you...

Thanks to all, having now seen the mass of voltage variants, I'm glad I live in the UK/Europe. SANDITECH

Hi I am trying to find the common voltage level(LV)of medium to large industrial plants in North America. All I can ascertain at present is a domestic level of 120V 60Hz P-N. Which based on the standard UK distribution sytem would give 210V P-P ? But do industrial (petro-chem) use this as there...

In basic terms Unrestricted earth fault protection detects all earth fault current downstream of the device. In the case of a main Incomer breaker it provides back-up protection to the feeder breakers on the switchboard as well as the protection for the bus bar system on the switchboard. I would...

The problem you appear to have has been well documented in the past. Basically at transition the phase voltage has not fully decayed before the line voltage is applied and depending on the instance of transition the contactors can have an increased voltage across one pole. All modern...

In the UK (using BS88 HRC fuses) I have always used the rule of a minimum fuse of 4 x the rated primary current. This has always handled the inrush current on countless control transformers. So for your transformer 4x(1500/490)= 12Amp.

I am not sure of the UK spec No (poss IEC439), but any circuit protected by a 16A SCPD, when proved by functional testing does not require a Megger / Hi Pot test. This rule is used within the UK panel manufacturing industry to negate the need for protracted testing on multi cubicle switchboard...

I am at a site where a 6Kv/0.4kV 1.25MvA Cast Resin Transformer is being fed by 7kV (Utillity Co will rectify soon?). What affect would this increased voltage have on the transformer? More with respect to heating than degregation of insulation? Its is intermittantley run at 6% of load capacity...

The simple reason the transformer has a higher kVA rating is that is allowed to run at a higher temperature, by taking more current the transformer will produce more heat losses I2t etc. Provided the unit has a dual rating design it should be able to run at the higher load. Cast resin units...

The Transformer will be out of circuit on the running drive as it is only switched in during the starting period. So it should be running on a Main Contactor only. I would check load variations fist then the Motor Power Circuit connections.