Speed relay

Hi,

Anyone here who can shed a light about speed relay?

We have a speed relay that was used to detect the speed of the genset. Here are the terminals specs:

2-7 DC supply 24V
4-5 AC input 2V~300V
1-3 H 2070 rpm
6-8 L 450 rpm

As far as I understand itH and L will be ON if they reach the set value. This will be detected on the AC input terminals 4-5. The dials for H and L are from 0-10.

Does the device sense only the voltage input on 4-5 or both the frequency and voltage?
Does the dials for H and L represents the tolerance for the set value?

Thanks in advance

paw

paw said:

2-7 DC supply 24V
4-5 AC input 2V~300V
1-3 H 2070 rpm
6-8 L 450 rpm

As far as I understand itH and L will be ON if they reach the set value. This will be detected on the AC input terminals 4-5. The dials for H and L are from 0-10.

Does the device sense only the voltage input on 4-5 or both the frequency and voltage?

Does the dials for H and L represents the tolerance for the set value?

Click to expand...

Not knowing what make and model you are using, I will take a guess at this.

DISCLAIMER: THIS MAY NOT BE 100% ACCURATE!!!

2-7 are 24 volt DC power source to the relay

4-5 are voltage input from some sender or magnetic pickup. If not, perhaps this is an addition power source for the relay to operate off 120, 208, or 240 volts instead of the 24vdc. Do not hook up AC voltage here if you do not know for sure!

1-3 H 2070 RPM This is the oversped contact, which when closed, will cuase the overspeed circuitry in the cranking panel to shut the engine down before it "launches" into orbit. Normal engine rpm is 1500 rpm for a 50hz genset, 1800 rpm for a 60hz genset, and somewhere around there for a pump or mule operation.

6-8 L 450 RPM This is the crank termination contact to tell the cranking panel to shut off the starter moter, and perhaps switch the low lube pressure circuit on.

I suspect that you are correct in the dials set the two setpoints. When the speed passes the setpoint, that contact will close.

Normally, a speed relay does not detect the voltage or the frequency. I often felt that they could, since 30 rpm translates to 1hz in this case.

Perhaps if you have a make and model of the relay or engine, you can get more detailed information.

regards.....casey

casey,


You are right the, 2-7 is for the dc supply, the terminal 4-5 are connected to the generator output, they were tapped on the U-V terminal of the generator.

The L output were use to swicth ON the relay between the alternator and the battery, for charging and also for the fuel level and oil temp unit and also to switch off the cranking circuit.


The manufacaturer is IIZUKA DENKI SEIKUSHO CO. and the model is
AG-R N. I could not find it on the net.

Is there a way that I can test this if it still working?


Thanks,

paw

the terminal 4-5 are connected to the generator output, they were tapped on the U-V terminal of the generator.

Click to expand...

YUK!! Appears to be a full voltage/frequency type. Much prefer a mag pick up type.

Underspeed is normally on at rest with most speed relays. Similarly, overspeed is normally on when NOT in overspeed with most speed relays (fail safe - if the relay fails overspeed comes up).

IF it is a full voltage/frequency type, you should be able to test the relay with a sine wave voltage/frequency generator within the bounds of the input limitations. 50hZ = 1500 RPM, 60hZ = 1800 RPM etc etc. Overspeed is normally calibrated at either 10% or 15% over run speed. This equates to a run speed of 1800 RPM (60hZ) plus 15% = 2070 RPM. Underspeed is not underspeed I would suggest but is an "above crank speed" signal to cut out the starter motor.

It appears that the AC is supplying the "speed sense" to the unit.

To test it, the AC will have to change frequency.

It will need 15hz to close 450 rpm, and 69hz to close 2070 rpm.

Or, supply 50 or 60 hz to it, and adjust the dials until tohe contacts open or close. Problem here is that will mess up your settings.

In theory, if you returned the dials to the exact same position, they "SHOULD" be the same, but that is not always the case.

While not "accurate", they may be close enough to suit your application, but then again, maybe not.

You may be able to check the 450 during startup.

I don't think that is advisable to run the engine up to 2070 to see if it shuts down. While I haven't seen on blow at 2100rpm, there is always the chance. I have run some CATs up to 2050-2075, some of the HUGE Cummins and Detroits to 2200-2300.

I did have a large Waukesha run away on me due to a shorted mag pickup wire, but we were able to cut the fuel hose to shut it down. Three 20lb CO2 extinquishers couldn't stop it, and when someone cut the battery cable, it kept going. Only time I ever RAN fom an engine. Really RAN!

Perhaps someone has a frequency generator that can put out a few volts that you could put in place of the AC line.

regards.....casey

Thanks Guys,


So it actually sense the frequency on the AC.

Our genset and its automatic control panel was made by DENYO.
The engine is Komatsu.

I'll if I can try your advice.

regards,

paw

I have used some Komatsu engines on smaller mechanical drive Komatsu mining trucks.

The larger mining trucks Komatsu made were "electric drive", with a GE locomotive traction drive system. Engines were 1200-2500hp, with my masterpiece having been a 20 cylinder 2500 hp Detroit. With 12 foot high tires, they brought a new meaning to the term "Monster Truck"!

best regards.....casey

currently there is trouble in our genset..

First the starting relay does not switch ON, when we check it out we found out that there is something wrong on the electronic circuit attached to it, then we remove it and connect directly the coil terminal of the relay to the supply and it switch ON.

The elctronic circuit of the relay has actually three terminals, R, S and G. R is connected to the R terminal of the alternator I think this to make sure that the starting relay will be OFF after starting. The S to the battery and G to Ground.

Second the control panel does not turn automatically and does not want to transfer power even using it on manual. We found out that there is something wrong with the sequence controller.

paw

CaseyK said:

Engines were 1200-2500hp, with my masterpiece having been a 20 cylinder 2500 hp Detroit.

Click to expand...

For some odd reason, I have a feeling you might enjoy THIS PAGE, Casey. Just a tad shy of 109 THOUSAND horsepower..



-Eric

CaseyK said:

Engines were 1200-2500hp, with my masterpiece having been a 20 cylinder 2500 hp Detroit.

Click to expand...

Series 4000?


A couple of years I built some hydraulic assembly gages to install the crankshaft and main bearings at DDC Outer Drive. That was fun. Took a while to run off; they build only 1-3 a day.

Thanks Eric, very cool link.

The biggest I got to play with myself are the 6000hp engines for the SD90 series of locomotives that Electro-Motive developed in the 90's, originally for Union Pacific.

6000hp probably isn't even a good starter motor for that monster you linked.

I even had a PLC on the locomotive. I felt there should be more. Must have been over a dozen embedded controllers.

EMD was a fun place to be if you liked big power, odd ball controls, or just had a "one track mind" about trains.

regards.....casey

Casey,
The biggest I ever got to play with was 2 20-645's. Had them on a dredge, Had a set of eaton air clutchs on the input of a reduction gear from a old navy destroyer going to a 30 inch pump with a 112 inch impeller. Did like it when you got them loaded and the trubo's would begin to sing.
Regards,
Tom

twbtxnca said:

Did like it when you got them loaded and the trubo's would begin to sing.

Click to expand...

Turbo's have been the fun part of engine testing over the years.

Before I moved back "north", I lived three doors off the old ICG mainline in bloomington, IL. I think UP aquired it from SP. I was about a half mile south of the "yard", and one night when they were getting the consist together, the 6 locomotives pullded the first batch of cars, and they were about even with my street. There were six different models of locomotives, a couple of 569's, a couple of different 645's, some with out turbos, so when they ramped up, it was kind of like a barbershop sextet. Wish I had a recording of it.

I got to do a few turbo projects, one was removing the oil pressure switch from them. So now, if there is no oil pressure, they will continue to run until they burn up. I didn't agree with it, they saved $15 per unit, on 250 engines a year. Somebody got big $$$ for the idea. Oh well. If one burns up, I hope they take the repair cost out of his pension.

regards.....casey

Turbos are very interesting things. Had one blow on load test one night. Brand new 2 MW set and all of a sudden the thing dropped it's load against the mains. It was fully loaded. Heard the note change in the turbo and opened the breaker. Black smoke for miles. Cab rang the fire brigades as he thought the building was on fire.

When commissioning a base load power station, we had a 4.1 MW set loaded to 4.8 MW on load test. The guy who ran the power station told me to come out to the set enclosure with him. He turned off all the lights and you could see the turbo fan rotating inside the casing - the cast iron at the back of the turbo was translucent. You could even see the exhaust gases rotating inside the exhaust pipes on the side of the engine as the cast iron was translucent.

The dredging company I workedfor had 32 EMD's some turbo some roots blowers, never had any turbo's go bad but because of the load( a dredge pump) we did have a lot of trouble with the sprag clutch on the emd's all would be fine and then the load would come up and the turbo would come off the clutch and then when the load would go down it sounded like a log chain beining pulled from inside of the engine and plenty of black smoke and time to restart. Kept life insteresting.
Had a Cat 399 gen set on a steam dredge and had to run it up to full load one time because we lost the steam gen set,well to make a long story short the exhaust was run up through the 3 decks above it and it was too much back pressure and the turbo's on it were birght to say the least. Turned the lights out in the compartment it was in and you counld read a book from the light of the turbo's. It is a site to see.

Regards,Tom B.