I'm working in merchant navy ships, Ship have three generators onboard. I'm having doubt, that in main switch board there is synchroscope for parallel generators. There is no lamps(for dark lamp and bright lamp methods to snchronize generators) if the synchroscope fails. Is there any practical methods to find the phase between bus bar phase and incoming generator phase(because the two phase should match). The frequency and voltage can be find out in meters.

 

Why not wire some lamps as a backup?

 

Why not wire some lamps as a backup?

First of all, While onboard we cannot get whatever we want like in shore. For wiring such connection directly need 440V lamps (In ships we can't get) Even transformers for converting 440 to 220 or 110V also we can't get. Is there a way to check with multimeter?

 

What is the highest voltage of available lamps? Can you series to appropriate voltage?

 

What is the highest voltage of available lamps? Can you series to appropriate voltage?

This can be done. Is there any other method to verify the phase. In case of emergency it will take some time, that i have to tap line from bus bar and the incoming generator line.

 

Just like the light bulb (dark), you can null a DMM by measuring the same points.
You can use a Lissajous pattern on an oscilloscope.

You will be making a difference measurement.

Below are three examples, 180 deg phase difference, 10 degrees, and 0.1 degree. Note the voltages across each generator. Both generators are set to 622.16V peak (440 rms).





What is your normal standard for switching using the synchroscope?

 

Just like the light bulb (dark), you can null a DMM by measuring the same points.
You can use a Lissajous pattern on an oscilloscope.

You will be making a difference measurement.

Below are three examples, 180 deg phase difference, 10 degrees, and 0.1 degree. Note the voltages across each generator. Both generators are set to 622.16V peak (440 rms).

View attachment 133653
View attachment 133654
View attachment 133655

What is your normal standard for switching using the synchroscope?

In this way i can use DMM, We use 440Vrms. Thanks for your valuable reply, This is the answer i expected.

 

I don't think there's too much you can do underway. Any particular reason you suspect a failure?
Request the engineer to have it done. Show him the situation. The cost is minimal.
That's a terrible engineering practice, especially on a ship.

 

I don't think there's too much you can do underway. Any particular reason you suspect a failure?
Request the engineer to have it done. Show him the situation. The cost is minimal.
That's a terrible engineering practice, especially on a ship.

If synchroscope fails on one generator, i remove the synchroscope of another one (which is standby or not using for a while) and connect it here, In some cases we have to use all three generators at a time, at that situation if one of the synchroscope fails i have to do something.

 

I too think it's not wise unless you have brought the phase voltage test points to where you can attach the DMM leads. I would not want to hold them, or have someone else hold them while underway.

If synchroscope fails on one generator, i remove the synchroscope of another one (which is standby or not using for a while) and connect it here, In some cases we have to use all three generators at a time, at that situation if one of the synchroscope fails i have to do something.

If your planning for the future, bring the test points to where they are easily accessible and SAFE. Do this modification when your docked. The ass you save may be your own.

 

I too think it's not wise unless you have brought the phase voltage test points to where you can attach the DMM leads. I would not want to hold them, or have someone else hold them while underway.



If your planning for the future, bring the test points to where they are easily accessible and SAFE. Do this modification when your docked. The ass you save may be your own.

Thanks.

 

You have one synchroscope for each generator? Do you have or can you get the panel emergency operations manual? Can your synchroscope be pulled while generator is loaded?

The last generators I put on line was done with Lissajous patterns on a scope. But that was built in...and I wouldn't consider it an operational back-up here.

I hadn't heard of the resistor/meter solution. Good to know.

I would still request panel lights.

 

@BR-549 I hadn't given it much thought but when I remembered the synchronizing by the lamp, it hit me all they were doing was nulling the signal. I nulled (20 dB quieting test) in comms receivers with a meter. Why not here? So I went to test it.

You could do a differential test with an oscilloscope as well. You would maximize the signals to be in phase, unless you inverted one channel, then you would minimize.

If you could drop the levels down to TTL, you could build a conditioning circuit and an exclusive OR to put them in phase.

Many ways to accomplish the task.

 

I hadn't heard of the resistor/meter solution. Good to know.

The resistor in my diagram represents the load on the generators. Yes, I know 200 ohms was a ridiculously high load.

The DMM measures the difference in the voltages on the selected phase of both generators. You must use the same phase on each generator.

 

The resistor in my diagram represents the load on the generators. Yes, I know 200 ohms was a ridiculously high load.

The DMM measures the difference in the voltages on the selected phase of both generators. You must use the same phase on each generator.

On-board there will be no oscilloscope, I can only use DMM. Thank you for you valuable reply.

 

Your meter and probes would need to be able to cope with a differential voltage of up to twice the peak generator voltage.

 

Your meter and probes would need to be able to cope with a differential voltage of up to twice the peak generator voltage.

Yes i'm using CAT 3 multimeter cope up to 1000V.