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Author Topic: One phase not working  (Read 281 times)

Bilbag

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One phase not working
« on: October 31, 2020, 07:42:47 PM »
A friend has a generator where one phase has stopped working. The phase not working is the one supplying the 240v output. The 3-phase does not work. If the 240v outlet is switched to one of the working phases to supply 240v, will running the generator like this cause further damage? 3-phase not required

scott p

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Re: One phase not working
« Reply #1 on: November 03, 2020, 05:36:27 PM »
Hello Bilbag: Are you a Hobbit?

Getting 220 from your machine is probably possible but you shouldn’t just wire things up with out doing a little investigating.

You need a good multimeter to start.

How many wires (leads) are coming out of the generator?

Bilbag

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Re: One phase not working
« Reply #2 on: December 02, 2020, 05:25:30 PM »
The generator is a Mecc Alte ECO28-VL4. It is a 12 wire system. It is a Stephill generator but cannot find their model number on it. I can work on it no problem and have good test gear. UK location so 240v and 50Hz.  I have had a quick look at it and there is 220v between L2-N and L3-N. the 240v output is from L1. The owner only used it for a 3-phase supply but he now has a mains 3-phase supply fitted so the generator is no longer required. I would only be using it for 240 supply. My concern is that if one of the windings for L1 has broken down, will using it and taking the 240v supply off L2 or L3 make it unstable. Also a concern is that the 110v supply for the regulator is from the fields on the L1 supply so that will also have to be moved to the L2 field. For me to investigate it properly I will have to get the unit moved to where I can take it apart under cover to trace the exact location of the problem. There is a voltage selection switch and I suspect that the problem may be in that. Not quite sure of the exact reason for this switch as in other generators with only 3-phase and a single 240v output they have no switch.  There is a considerable cost to get it moved as it is mounted on a skid base so requires a forklift to move it on and off a trailer so to do this I want to be sure I will get some use out of it.

AdeV

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Re: One phase not working
« Reply #3 on: December 03, 2020, 09:44:30 AM »
A friend has a generator where one phase has stopped working. The phase not working is the one supplying the 240v output. The 3-phase does not work. If the 240v outlet is switched to one of the working phases to supply 240v, will running the generator like this cause further damage? 3-phase not required

It depends on how it's failed. If it's shorted internally, then it'll heat up and catch fire - which wouldn't be ideal.  If it's failed open circuit, then it shouldn't do any further damage, it's just a dead leg. You'll lose some efficiency (i.e. excessive fuel consumption), as the engine is dragging a dead phase around, but assuming this is just an occasional use set, that's probably not an issue.

All three phases should be giving out the same voltage - i.e. 220 across the board, or 240. The specs for 240v AC power actually allow anything from 220 to 250, so even at 220 you're (just!) in spec.

Machine Mart occasionally sell reasonably priced 3-phase alternators (I think they're Mecc Alte branded), they also do 240v ones, but for some reason they're more expensive, IIRC.
Cheers!
Ade.
--------------
1x Lister CS Start-o-Matic (complete, runs)
0x Lister JP4 :( - Sold to go in a canal boat.

Bilbag

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Re: One phase not working
« Reply #4 on: December 03, 2020, 02:50:22 PM »
Thanks, will probably arrange to get it moved to inspect properly. Engine good anyway.
Cheers