Unsure of exactly what the question is asking and how to answer it!

[Meg464]

Hello, I'm a little stuck on assignment 303, id appreciate a little shove in the right direction, I'm not looking to get answers, just need to pick your brains to get on the right thought track as the questions are worded oddly on some of them and I think I'm over complicating it!!

7b) Likely faults to do with transient over voltage on the supply.

8b) Faults most likely to occur in instrumentation in the intake position.

9f) A number of areas within the nursery require special precautions to be taken during fault finding. Identify these precautions in relation to the following. High frequency or capacitive circuits.
(I'm thinking along the lines of capacitor banks and current discharge)

Thanks in advance if anyone does manage to get back to me on this!

 

[Pete999]

Think of Safe isolation during dead fault finding, lots of technical equipment, wouldn't to be throwing 500v DC at that lot without careful consideration, most of the machines will have HF and capacitors includd in their innards, as for instrumentation not sure what they mean eaither sorry. Could be they are after faults like current transformers going open circuit, hope that throws you some ideas. Good luck

 

[Bobster]

It would help to see what you think the answers should be. Don't be worried if they are wrong.

It often cements the knowledge if you come to the answers yourself with people here steering you in the correct direction. Rather than just giving answers away.

 

[Meg464]

For 7b I'm not entirely sure what is meant by transient over voltage as I've not heard the term before I'm thinking possibly along the lines of over voltage that comes and goes?

8b I'm not sure at all what is meant by instrumentation in the in take position? Could it be computers/instruments plugged in therefore in the intake position? If I can understand the terms in the question a little better it will help me get my thoughts on the right track!

And 9) is that basically asking what damage could occur i.e. To equipment with high frequency capacitors and being plugged in during a dead tests and damaged being cause as they are sensitive to high voltage?

Thanks again guys!

 

[Abruno]

7B would be possible damage to the installation. If an installation was designed for 230 volts and say natural occurrence a lighting strike was to hit the installation a higher voltage could be induced onto the installation that was designed for 230 volts.
For example, an electric light bulb has a wire in it that at the given rated voltage will carry a current just large enough for the wire to get very hot (giving off light and heat), but not hot enough for it to melt. The amount of current in a circuit depends on the voltage supplied: if the voltage is too high, then the wire may melt and the light bulb would have "burned out real time". Similarly other electrical devices may stop working, or may even burst into flames if an overvoltage is delivered to the circuit. Hope this helps

 

[Bobster]

7B would be possible damage to the installation. If an installation was designed for 230 volts and say natural occurrence a lighting strike was to hit the installation a higher voltage could be induced onto the installation that was designed for 230 volts.
For example, an electric light bulb has a wire in it that at the given rated voltage will carry a current just large enough for the wire to get very hot (giving off light and heat), but not hot enough for it to melt. The amount of current in a circuit depends on the voltage supplied: if the voltage is too high, then the wire may melt and the light bulb would have "burned out real time". Similarly other electrical devices may stop working, or may even burst into flames if an overvoltage is delivered to the circuit. Hope this helps

Think you need to work on some terminology in that statement.

Also refer to V=I/R, higher voltage would be less current.

 

[Abruno]

Think you need to get a life

 

[FatAlan]

V=IxR

 

[GMES]

Let's not start squabbling and get back to helping the OP, cheers.

 

[FatAlan]

What's the course Meg and is there any more context to the questions, i.e an overriding scenario?

 

[Lucien Nunes]

Transients - i.e. spikes, don't last very long but can cause stress insulation beyond its voltage rating and cause heavy currents to flow. What sorts of damage might result from those effects?

Instrumentation in this context means metering / monitoring equipment. Why might equipment at the origin have a different experience of life than something plugged into a socket outlet?

Capacitors (and circuits with high capacitance) store charge, and if they don't have discharge resistors inbuilt and the IR is very high they can remain charged to a high voltage for a long time. What kind of faultfinding procedure might leave them in that condition?

 

[Deleted member 26818]

With voltage spikes, I'd expect blown fuses and incandescent lamps if lit.
Intake instrumentation damage would be the meter would stop measuring.
With capacitive circuits, I'd be shorting the conductors to earth before and after each test.

 

[UKMeterman]

As for the intake do a bit of research on the misswirng of current transformers and so on.