Generator / supply problem

[Knobhead]

It would be interesting to know Phil.

 

[Lighthouse Phil]

The speed governors were checked on all 3 engines at a very recent over haul. The mech fitters stripped the engines down to thier underpants and rebuilt them. The engines are now as good as they were when first bought. (so they tell us).
The fitters knew we were having what we first thought of as frequency problems so they (the governors) were set for a electricial load of 30A, the frequency matched to suit. (50hz at 230V, 30A load). The engines are normally set for 51Hz as this falls away at load, as does the Volts.
To answer your Question E54, the engines are controlled normally from a photocell, via a PLC, so that when the Main Light is called for, 1 of the engines start. This would supply the light and other navagational aids. (Its a lighthouse by the way).If this engine were to fail for any reason the control cabinets would detect a loss of power and start engine 2. Likewise, if this engine were to fail, engine 3 would start. When people are staying at the lighthouse for maintenance works, 2 engines can be run, 1 to supply the Light (called the A load), the other to supply the dwellings (called the B load). Loads can be split form a distribution control cabinet.
Under normal operating conditions when no one is at the station the load would be around 25A. 5A for the light, (1000W) 20A for a storage heater and battery chargers. The engines dont like working without a load so we install ballast loads (storage heaters etc), the maintain a decent loading on them.
During the maintenance visits we would keep an eye on the running time of each engine and decide which engine should be the main one (No.1) until the next visit. It would not be uncommon for a genset to run for 3 or 4 months constantly. ( we have long running oil sumps on each one)

 

[Engineer54]

Thank's for the heads up on the operation set-up...lol!! Though i would of thought a flip over control circuit would be a better system of selecting the prime generator. The overall wear of each gen-set would then be far more near equal, to each other... eg, Prime generator sequenced at every start....

Getting back to your problem, it's got to be something that is common, that all 3 Genny's will see then!! Which will include the load control panel, main lighthouse supply cable(s) and the distribution loads within the lighthouse. You can virtually rule out the individual gen-set control/protection panels, as it's unlikely that all 3 will have the same fault (not completely unheard of though...lol!!)

By the way, how do you achieve the extra +25A to the +50A load, where you say this problem starts showing itself??

You are so right about gen-sets not liking to run on low loads. These are generally spec'd by inexperienced Electrical Engineers or Mech Engineers, who really should know different, as it's the driving engine that is effected/damaged, rather than the alternator!! lol!!!

 

[Knobhead]

Got to admit I’m surprised there’s no auto cycling of the sets, especially as there is a PLC present.
The way the weather is at the moment, a job on a remote island sounds ideal. OK I know there’s always a downside, foul weather is never far away.

 

[Lighthouse Phil]

Will be going back out to this Lighthouse in a few weeks and I plan to do lots of different tests on the wiring side of everything. Personly I'm 100% happy with the gensets, as all 3 have new AVR's and are newly rebuilt.
The extra loading comes from us guys living at the station, we would have the usual domestic loads on, ie, TV, lights, fridges/ freezers etc. (I was thinking about the motors in the fridges/freezers -- maybe something will show up when they are PAT tested)
I'll keep you posted as to my findings and will include some photo's. If I can, I'll post the Vlog graphs on here too.

Thanks to ALL for for inputs / advice.

Phil