The DG is built as a back-up system and as such, may be seldom used.
Every once or twice a year, the DG need to be serviced. It will be disconnected from the critical load during maintenance. This is when you use the built-in load bank to test the genset and ensure that it is still working properly.
Load banks are also used if the connected load is so light it causes problems with generator governor regulation. Common on big yachts. This is more of a problem with older type engines. But at very light load the genset engine does tend to get piston blow by and the regulator causes Eventually it leads to cylinder wall glazing. The solution is to use a load bank. Sometimes this is merely hot water tanks or hot air heaters if the byproduct can be used somewhere. Otherwise it is pure wasted energy.
I once visited an engine rebuild shop and they had a load bank that could absorb the full output of a 6000 HP diesel train engine being tested in the dynamometer cell prior to being put back to work. Very impressive! Engine running full throttle and going nowhere. The load bank was on the roof and fans blew cooling air through the resistive load bank.
I once had the opportunity to do a dyno test on a 492 HP Detroit. It was installed in a truck. The rollers were narrower than the tread by 6 inches. That truck hopped and screamed like I had never seen it do before. The bay it was in was closed in the back and the truck has no muffler. LOUD was the name of that game.
You had to use ear protection. Even so the physical vibration transmitted through the floor was something else. One time at sea I visited the ship's engine room. Four GE engines in parallel drove the generators that in turn drove the propeller. It sounded like a million marbles rattling around in a steel can. and that was with ear protection on. You would be deafened in 30 seconds with permanent hearing impairment if you took off the ear protection. By comparison steam power was so much less noise. Even at the same amount of horse power. But the boiler's forced draft does get noisy.
The amount of heat generated in the load bank is immense. Too bad is can seldom be put to use.
szwasta; we built reconnectible 3 phase load banks for voltage up to 600 volts, both in resistive & reactive loads, with trimming to adjust phases, the largest was a 1 megwatt resistive that could be turned with 1 switch, boy did that engine bark. pc
Large diesel engines especially for gen-sets where the engine is lightly loaded but still needing to run at a fixed high RPM have trouble with the fuel control injection pump.
The load factor of 30% suggest the load bank is intended to assist when the electrical load is at a bare minimum. Switching in the load bank to bring the load seen by the gen-set helps regulate and stabilize the output and allow the diesel to run smoother.
If I was a ship's engineer for example, I would be switching in such a load bank at night when the hotel loads dropped to a minimum. This will ensure better service life because a 30% load will prevent wet stacking which leads to glazed cylinder walls. Power generation facilities always have a problem with maintaining base load above a certain minimum.
Wanted: Diesel Generator (DG) Load Bank
Re: Wanted: Diesel Generator (DG) Load Bank
