Speed relay

[BobB]

Had a Cat 399 gen set

Just finished commissioning a re-hash with 2 of these old girls. They still have the stupid pressure start system on them. Just get away on the last crank. Needs ripping out and replacing with an electric pre-lube pump that runs every 8 hours or so for a few minutes.

 

[twbtxnca]

Bob,

Have you ever had a 399 with a woodard UG 10 ( I think that was the number was one of the first electronic gov's they made.
If you didnt watch out it was to fast for a cat you would look up at the control rod to the rack and it would be doing a jig way to fast for the 399. In fact there was one that another dredge had and they had set to much gain in it and to galded the rask and it stuck when it went to full load. Wasnt alot left when it blew. Parts were al over the place luckly if wwas down in a lower compartment and no one was close to it sent parts all the way through a 3/8" bulkhead.
very nasty.
Regards,
Tom

 

[BobB]

woodard UG 10

Deadly b****y things. I would throw one away as soon as I saw one on a set these days.

One of my customers was really lucky with a UG8. He was alongside the set when a manual start was performed after a service. The UG8 went berserk and he had to grab the actuator arm and drag it back. The set eventually stopped on a software underspeed. The mechanical overpseed would not have worked. About a $2 1/2 million AU engine (large Ruston). That would have been scary.

In fact there was one that another dredge had and they had set to much gain in it and to galded the rask and it stuck when it went to full load.

Very easy to do particularly with the old analogue stuff.

Wasnt alot left when it blew.

Saw that happen to a "Blacksmoke" (Blackstone) one day. Man, you really need to run for cover when that happens. Someone defeated the mechanical overspeed!!!!!

 

[paw]

I had my training during college on a diesel power plant. Sulzer engines, air lift, driving 4MW generator. It is an old power plant.

Anyway I have this question in mind that I could not answer. Our genset speed is controlled manually by a throttle handle. When operating at no-load the engine consumes only a little amount of fuel, however at load condition the engine consumes a lot of fuel.

Why is this happening?



regards,

paw

 

[jstolaruk]

... When operating at no-load the engine consumes only a little amount of fuel, however at load condition the engine consumes a lot of fuel.

Why is this happening?

Not trying to be a smartalec but isn't the engine performing more WORK. Thus requiring more energy?

 

[paw]

does the load of the generator affects the mechanical output of the engine? how?

because there is no automatic control for speed of the engine and the load of the engine is only the generator.

 

[jstolaruk]

does the load of the generator affects the mechanical output of the engine? how?

In a nutshell or laymen's terms:

A generator converts mechanical energy into electrical energy. The magnetic interactions of an armature, rotated by the engine, in stator windings creates an electrical current. When a demand is made for more electrical current, the magnetic coupling transfers this demand by increasing the magnetic load or counter force on the rotating armature. The engine, trying to maintain a constant RPM (or not in your case) of the armature, has to use more fuel to overcome this resistance.

FWIW I hope that helps.

 

[paw]

jstolaruk,


so the magnetic field created by the load current, counter acts the rotation of the rotor and that causes the engine to produce more work in order to maintain its speed.


thanks,

paw

 

[jstolaruk]

Paw, after thinking about it a little bit, I believe my description may be flawed. Instead, I would expect that a monitoring circuit measuring the current demand would regulate the engines rpm by increasing or decreasing fuel. More energy out requires more engergy in. -Jeff

 

[paw]

ok jeff, thanks once again


paw