Changeover for Mains Failure

Hi Everybody,

I'm doing a project for my BEng Course and my theme is control of a remote area lifting station. All the pumps and changeover mains failure are controlled by a PLC (Sofrel) and SMS are relayed to mobile for any faults, etc.

I have 2 phase monitor (one for the utility and one for genset);
(1) Firstly, I would like clarify if the phase monitor should be connected before the circuit breakers or after.
(2) If the utiliy (mains) power is available but the circuit breaker is tripped, shall I order the genset to start or just send an sms that the circuit breaker is tripped but power is available.
(3) If I switched off the utility circuit breaker even if the utility supply is available, should the genset start.

(4) If you can just briefly described a control philosophy (flow chart) for a PLC control of changeover for an idea.

Thanking you in anticipation.

Regards

If you only have to phase monitors then i would think it would have one would have to be put before the breaker. I would think that if it was after the breaker and the breaker tripped and you started up any generators that it may cause problems for you and the power company(mainly you). That is unless i am not getting the overall idea of said idea.

I'd look at a few manuals for Automated Transfer Switches, this is a fairly complex control as you need to know the state of the Utility feed, state of the gen feed and state of the breakers. I wouldn't recommend starting the Genset when the main breaker has tripped, they generally trip for a reason.

You'd need some kind of contactor/transfer switch in the system, as the very last thing you want is utility power coming back with the genset feeding at the same time, its one really fast way to destroy a generator.

Oh, we don't like to do your projects for you, we'll help if you show some effort but we won't just do them.

See this website for some ideas, this company has been doing this for a very long time.
Link:
http://www.emersonnetworkpower.com/...rols/PowerTransferSwitches/Pages/default.aspx

(1) Firstly, I would like clarify if the phase monitor should be connected before the circuit breakers, or after?

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Most electrical codes require an upstream breaker, but if this is a utility service and it is more dangerous to install the monitor downstream, there may be an exception to the code requirement. Fire pumps fall in this category, so if your lift station "not working" would have an equivalvent hazrd, then maybe you could install your power monitor upstream of the main breaker. In most cases, probably not!

(2) If the utiliy (mains) power is available but the circuit breaker is tripped, shall I order the genset to start, or just send an sms that the circuit breaker is tripped but power is available.

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Send an sms that the circuit breaker is tripped but power is available.

(3) If I switched off the utility circuit breaker, even if the utility supply is available, should the genset start?

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No.

why not use a gasoline powered pump then if you have a power or wiring failure you can still pump out your lift station. you could use a battery powerd plc run off the battery on the pump use seperate level controls .just a thought