UK Stationary Engine Forum
 

Go Back   UK Stationary Engine Forum > Main Engine Section > Engine-Only Stuff > Generators

Reply
 
Thread Tools Display Modes
Old 30-12-17, 10:56 AM   #31
listerdiesel
Admin Team
Forum Supporter
 
listerdiesel's Avatar
 
Join Date: Feb 2008
Posts: 15,920
Default

We run the 2.5kVA Start-O-Matic alternator on the Ruston 1ZHR as a standalone generator with electric starting.

Everything needed was in the box on top of the alternator.

Details in the Ruston 1ZHR thread:

http://www.stationary-engine.net/for...ead.php?t=7229

Hoping to use a 4.5kVA Start-O-Matic alternator on the Petter 18hp S Type if all goes to plan.

Peter
listerdiesel is offline   Reply With Quote
Old 04-01-18, 12:48 AM   #32
Lucien Nunes
Forum Supporter 2011
 
Lucien Nunes's Avatar
 
Join Date: Sep 2009
Location: London
Posts: 874
Default

Auto sequence and possible problems...

When S1 is at Auto and the plant is at rest, the detection circuit monitors the load with 24V, waiting for a circuit to be completed to initiate the start. The circuit is Ammeter - K1 - LC4 - D - S1/2 - Load - Batt -ve. When a circuit is completed through the load, D (detection relay) operates, closing D1.

D1 energises FCS to allow the engine to start, and via LC3 energises SC (start contactor) to crank the engine and K (thermal delay heater) to begin the startup watchdog timing. SC1 completes the motoring circuit through the series field winding to run the generator as a motor, the set turns over and the engine should fire and run up to speed.

Once the generator is outputting healthy voltage, rectifier LCR and smoothing capacitor LCC deliver a high enough DC voltage for LC to operate. This is the most important moment in the sequence:

LC1 completes the AC circuit to the load, via CH (load choke) and S1/2. The load current passing through the choke develops a voltage across it, which is rectified by DR, smoothed by C and also applied to D.

LC2 removes the bypass from the ammeter and completes the charging circuit via CR, on the basis that if there is AC output the DC voltage must also be OK.

LC3 breaks the circuit to SC which stops operating the armature in motoring mode, and to K which stops timing the startup.

LC4 breaks the DC detection circuit, leaving D held on the rectified voltage developed across CH.

The set is now in full operation and will continue until the load current falls to a point at which the rectified voltage across CH will no longer hold D, which releases, disconnecting FCS, causing the plant to stop. As soon as the output voltage falls too low to hold LC, that releases restoring the complete circuit to standby and re-instating the DC detection ready for the next start.

If the engine failed to start, or it started but the generator failed to prduce enough output to operate LC, the feed to K would remain alive. Eventually K1 would open after the thermal delay, removing the feed from D to cancel the detection process.

It will be seen that there are two ways for D to be energised - DC from the battery to detect a load being applied while the set is at rest, and rectified AC from across CH, to detect the ongoing demand for current when the set is in operation. LC determines which of these is in use - when LC is released, LC4 enables DC detection while LC1 disables AC detection. When operated, this situation reverses. It is essential for the contacts of LC to operate in the proper mechanical sequence - LC4 must open before LC1 closes, otherwise the AC and DC circuits become connected together via DR which would rapidly fail in a puff of smoke.

If the DC detection circuit is faulty, the set can be started manually by operating D or pressing the manual start button S, and will carry on running while a load exists. This will also happen if the load cannot pass DC current, or is on the borderline of detectability. If the AC detection circuit is faulty, for example if the smoothing capacitor C is faulty, the set will start but then stop again when LC operates (changing the detection source from DC to AC). This may continue as a cycle, if D operates again when LC4 re-closes.

If LC is set much too sensitive, it might operate before there is enough AC voltage to drive a large enough current through the load to ensure D holds, causing the plant to stop as soon as LC4 opens. The same effect may occur if LC is manually operated too soon. No particular malfunction will occur if LC operates late, but if it fails to operate at all, K1 will halt the startup.
__________________
Anybody caught running Listers on veg oil will be made to eat a plate of chips cooked in red diesel

Last edited by Lucien Nunes; 04-01-18 at 12:54 AM.
Lucien Nunes is offline   Reply With Quote
Old 08-01-18, 09:52 PM   #33
Bravemeister
Forum Light User
 
Join Date: Oct 2017
Location: Yorkshire
Posts: 14
Default

Hi Lucien,

This write up is fantastic! I can finally work through and put arrows on my own replica diagram to work out how this all works!

Have emailed stationary engine parts and sleeman hawkin regarding a replacement LC coil - see what happens!

Regards,

Matt
Bravemeister is offline   Reply With Quote
Old 08-01-18, 10:08 PM   #34
Bravemeister
Forum Light User
 
Join Date: Oct 2017
Location: Yorkshire
Posts: 14
Default

Just reading through the bits at the end of your post, Lucien.

K1 is definitely working - I can start the set, it will get up to speed, tick over for 30 secs or so, then shut off.

The DC detection circuit also works as I can plug a 500W halogen lamp in, flick the switch and the generator will start to turn over and fire up once I move the lever (am yet to swap the rocker cover for the automatic decompressor one).

"LC4 must open before LC1 closes" From my investigations of the electrics, I believe that both LC4 and LC1 are opened/closed by the LC coil. In which case, LC4 opening before LC1 closing surely must be an instantaneous process when the coil kicks in..?

It does seem that my symptoms are somewhat similar to the last paragraph of your post. In my manually actuating the coil (Since it is open circuit), the engine quickly dies as the fuel control solenoid shuts off the fuel supply. As soon as I release the coil, fuel come back on and the engine runs back up to speed.

Will keep you all posted as soon as I hear anything from Sleeman Hawkin or SEP.

Regards,

Matt
Bravemeister is offline   Reply With Quote
Old 09-01-18, 01:44 PM   #35
Lucien Nunes
Forum Supporter 2011
 
Lucien Nunes's Avatar
 
Join Date: Sep 2009
Location: London
Posts: 874
Default

Yes, LC1 and LC4 are contacts of LC. The notation for relays is that a letter represents the coil, and can be used to refer to the whole relay, where the number of contacts is often given under an oblique. The contacts are numbered without the oblique. So, B/2 is the coil of a relay with two contacts, numbered B1 and B2.

Contacts can be made to transition in a defined sequence, even if the time differential is a few milliseconds. When I said LC4 should open before LC1 closes, both events occur as LC operates but specifically in that order. If LC dithers midway because the voltage is ramping up slowly, there must not be a situation where both remain closed at once. Nor should there be too long a break - the capacitor will hold D for a fraction of a second but if neither detection circuit is active, as soon as it has discharged D will release.

Your description of what happens when you operate LC manually suggests that the detection rectifier and/or capacitor are faulty. Once there is normal voltage output from the genny (all bets are off if you are doing this before it's up to voltage), when you operate LC the 500W AC load should hold D. It sounds like this is not happening; as soon as LC4 breaks the DC detection circuit, D releases, de-energising the FCS and stopping the engine (LC itself does not control the FCS).

Does the lamp light briefly when you operate LC? (terminology note - you can't manually operate a coil, what you are pushing is the armature.)
__________________
Anybody caught running Listers on veg oil will be made to eat a plate of chips cooked in red diesel

Last edited by Lucien Nunes; 09-01-18 at 01:48 PM.
Lucien Nunes is offline   Reply With Quote
Old 12-01-18, 08:42 PM   #36
Bravemeister
Forum Light User
 
Join Date: Oct 2017
Location: Yorkshire
Posts: 14
Default

I have had a response from both Stationary engine parts and Sleeman Hawkin. Unfortunately neither of them stock anything like the part I'm trying to source.

I got a reply from someone called Steve at SEP who suggested getting the coil re-wound and recommended a place called Majestic transformers in Poole.

I also got a reply from someone called Keith at Sleeman Hawkin who has put me in touch with someone that may be able to help - as of yet I've heard nothing back.

I will look for a modern alternative in the meantime and see if I can get it all going. If this works out then I'll look in to getting the coil repaired/re-wound.

Lucien, thank you again for answering my query.

In response to your last comment, yes the set DOES output and light up the halogen lamp, but obviously as soon as it does it, the light quickly dims and I have to let go of the coil.

When I first connected up the generator to the set, I hadn't connected up the FCS, so when operating LC the lamp remained on until I let go and then switch the engine off.

Regards

Matt
Bravemeister is offline   Reply With Quote
Old 13-01-18, 09:50 AM   #37
Lucien Nunes
Forum Supporter 2011
 
Lucien Nunes's Avatar
 
Join Date: Sep 2009
Location: London
Posts: 874
Default

Oh well, it was worth asking. A few times I have spent hours looking for second-best substitutes, later to discover that the original component is still available from stock.

Seeing as your lamp lights when you manually complete the load circuit, but D drops out, it appears that DR is faulty and most likely C as well (the rectifier and smoothing cap for AC load detection). The only other relevant component is CH but that is unlikely to be faulty. Personally, I would fix this problem before substituting an alternative part for LC, as it will hinder troubleshooting any snags caused by the substitution. I would check the wiring to make sure it is not simply a bad connection, inspect D for obvious damage, then replace DR with a silicon diode such as a 1N5408 and C with a like component such as Vishay Axial 47/63 cap at CPC

Restest to confirm that manually operating LC (once the generator attains normal voltage with a load connected) does not now cause D to release and the set carries on running and supplying the load all the time LC is held in. Then, it will be possible to test the correct operation of the substitute LC without the confusing factor of a faulty detection circuit.
__________________
Anybody caught running Listers on veg oil will be made to eat a plate of chips cooked in red diesel
Lucien Nunes is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 02:16 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.