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The issue on this vessel is not the loss of imperative equipment as any such equipment is derived from battery banks charged by an alternator on the main engine. There will be no shore power, even though the facility exists. Given that consideration and the fact that the neutral is distributed...

We have taken delivery of a 400ton steel-hulled dutch barge which has no less than 3 separate 3-phase 400/230v generators of around 40KVA. The control system is such that the generators cannot operate in parallel. Setting aside the 24v dc installation, the electrical installation is as you...

Sorry guys, I guess I wasnt too clear in my question. I am more interested in the typical magnitude of bolted earth fault currents on the 11KV network due to deliberate attempts to restrict them by LERs or other devices. For example, would it be usual to restrict earth fault currents to a...

I am interested to know the typical line to earth fault level on the primary of an 11KV/400/230v D/S Trfmr, the type generally used on the UK public distribution network. Where the tank earth and the secondary star-point earth connection are bonded the fault voltage appearing between the...

A single phase to three phase rotary-type converter installed on a farm to drive a compressor has assymetric voltages to earth on the load side. I understand that this is a feature of such devices. The displacement between phases remains at 120degrees. Can any one tell me why an equal phase to...

DPC many thanks for you reply. I am sorry to be thick but are you saying that if say my demand was 1Kw and sufficient wind was available for the turbine to output 1 kw, my utility meter would not be registering energy demand? Regards, Lyledunn

Thanks for the replies. There is no utility buy back and no batteries to charge. The point is that the load in my home rarely exceeds 1Kw thus with 2 available emf sources connected in parallel and if we suppose each had the same internal impedance then the load would be shared equally between...

May I bother you with a technical query slightly outside my capability? Consider a 1Kva wind turbine being fed on to a common single phase busbar also supplied by the grid via a standard 50Kva tx. Such a situation would be found in a typical domestic installation that has installed the micro...

Yes, thanks David, as pointed out by IRstuff there is ambiguity in the claim. My little knowledge of error theory recalled that accuracy is referenced to f.s.d. However, I read an article in a trade mag that alluded to the almost proposterous margin of error in some instruments designed for...

I have a new digital ohmmeter that claims an accuracy of 2%+-2digits on the 20ohm scale (19.9). The resolution is 0.01ohms. Does this mean that a reading of say 0.4ohms could be 0.18 or 0.62 resulting in a deviation from the measurand of circa 55%? Regards, Lyledunn

itsmoked. Just what sounds like a rabid dog? Regards, Lyledunn

Brian, The effect of a shock derived fom static in the situation described may well not have direct detrimental affect on the human body. However, many accidents have commenced with a mild shock that resulted in an involuntary reaction by the victim the consequences of which resulted in death or...

Cucky2000, Many thanks for your reply. I take it that the tx and genny are located at the receiving end? Regards, Lyledunn

Similar incident in a polythene factory where the pest control guy complained that he received a shock at the metal cases fly zappers! Tried it myself, no small discomfort- it was a mighty dig! As the operative walked through the factory charge built up on him only to be discharged at the...

As a simple interested observer, I am aware of the importance of the transmission angle in power transfer situations but what are the practical methods generally employed to adjust the transmission angle on 33KV lines? Regards, Lyledunn

Listening to a BBC news report where an "expert" was interviewed, it was suggested that the power of the hurricane was more than all the energy ever produced by mankind! Perhaps, regardless of the veracity of the anecdote (and I have no reason to doubt it), it is nonetheless very humbling to...

I have just perused a number of web sites relating to this issue. Perhaps I should have done this first off! My question is thus answered. Thanks any way! Regards, Lyledunn

Is there an electronic replacement/alternative for the IDMT relay? It has been quite some time since I worked in the industry but I was told that the good-old IDMT has been virtually shelved on new or refurbed protection schemes. Regards, Lyledunn

Thank you gentlemen for your kind responses. I see the kernel of what you are saying. I take it that the UPS own protection system operates in the event of a fault with no mains or gen set etc available. As such, where there are no minor downstream protective devices, how is it confirmed that...

Many UPS rely on switching to a bypass circuit when a load-side fault is detected. However, one primary function of the ups is to take the load when mains fails. Now I assume that the ups may not have appropriate energy levels to clear faults in the appropriate time, so what mechanism is...