Mains alternators

[solarman216]

Hi all I have a question, mains 10kva generator, is it OK to start it with load connected, or is it better to start and get up to speed before flipping the load on, I ask because for the last 5 years we have been doing the latter, and the alternator has still failed, with the old Lister unit we never bothered and had no problems, but I am sure some bright spark will drop in and say "it will set up eddy currents or such like" I am just seeking info, Rick

 

[rayf3262]

off load during run-up.
As you will not get 50HZ until the unit is running at sync speed.
Some units have a contactor that automatically switches the alternator output to load when sync speed is achieved.

 

[solarman216]

off load during run-up.
As you will not get 50HZ until the unit is running at sync speed.
Some units have a contactor that automatically switches the alternator output to load when sync speed is achieved.

Thanks Ray, when this new set arrives I will check it out to see if it has such a device, if not I will probably need to make/fit one as many times the Mrs will be required to start it and as it will be located in the Barn I will need to fit simple remote start, maybe the easiest way will be to fit a timer to say switch the load on after say 1 minute, this will also give it a little time to warm up, Rick

 

[rayf3262]

This device is not a badly priced at £26
http://www.charter-controls.com/pro...240vac-over-under-frequency-relay-1-c/o/4074/

 

[Lazy-Ferret]

Main problem with switching on under load is what it does to the devices connected to it. Some can be upset by starting with a low voltage or slow frequency. In theory it should bee better for the generator as it puts less of a load spike on it.

sent from my phone, sorry for any typo's.

 

[rustic]

Definitely start it under no load.:thumb2
You will be putting a strain on the starter as well.
The voltage will be low, and on some electronic switch mode power supplies ( Shown as a supply as 110- 240 on the label, ) they will be working very hard and under low voltage, this is when they can be damaged.

You need either a delay after startup, if automatic, or some sort of voltage sensing.
The problem can also happen on close down, as say it runs out of fuel.
Better to switch off early than go into "Brown out" ie low loltage condition.

During brown out, any motorised equipment might stall and burn out the motor or control electronics.

When a generator starts, it might go into overspeed for a few seconds, until the governor takes hold, and regulates the revs. This might produce high voltages and higher frequencies than some devices can take.