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Author Topic: UPS for fluorescent lighting  (Read 5943 times)
billi
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« Reply #15 on: August 03, 2009, 08:02:43 PM »

12 volt bulbs  on a battery ?
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tony.
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« Reply #16 on: August 03, 2009, 08:45:28 PM »

 sorry my 207 volts came from other european countries where they are allowed a 10% minus drop on the 230 supply.

we were looking at a few non uk specs the other week at work, thats why it stuck in my mind, that will serve me right for posting info without checking!

glad you seem to be getting on top of it!!!

all the best  tony
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tim_h
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« Reply #17 on: August 03, 2009, 09:42:20 PM »

I recently had a similar problem at a small engineering / fabrication works nearby. The lights in the offices would often flicker or go out for a few seconds when the "big" welders were used.
We knew the correct solution was to upgrade the submain feeding the unit from the mains incoming position, however this would mean trenching across 50m of concrete & tarmac yard, so we tried the sticking plaster approach of using high freqency electronic ballasts. The old fittings were 100w 8' standard battens, these were swapped with 6' twin electronic fittings. This worked really well, the electronic jobbies seem a lot more tolerant of voltage dips and we've had no complaints at all from the customer since fitting them.
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daftlad
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« Reply #18 on: August 03, 2009, 10:11:04 PM »

Tim
Brilliant.
Do you know the brand of the ballasts? I have been ratching around the net and I am sure some will take wider ranges of voltage than others.
I think the submain that is the real problem is the one provided by the leccy board.
thanks again
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I WILL KEEP BANGING ON ABOUT MASONRY STOVES
w0067814
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« Reply #19 on: August 03, 2009, 10:20:52 PM »

Your problem is caused by the excessive start-up current drawn by the motor.

If you measure the resistance across the coils of a motor, it shall be very low.

When motors are turning they are also acting as a generator, producing Back-EMF voltage(Electromotive Force). The Back-EMF is always slightly less than the supply voltage and is is impeding the current flow into the motor.

When a motor is not running there is no Back-EMF so the in-rush current of the motor is only limited by the winding resistance.

The motor current can then be approximated by:

Current = (Supply Voltage - Back-EMF) / Winding Resistance

Your best option would be to install a soft-starter switch - these can be bought as ready made items. If you are going the DIY route you could add a suitably rated NTC (Negative Temperature Coefficient) Thermistor in series with the live supply. An NTC Thermistor has a high resistance when cold, but a low resistance when hot. When the motor is off; there is no current flowing through the Thermistor, so it cools to room temperature and the resistance rises. When the motor is switched on; current flows and the Thermistor heats up due to ohms law (Power = Current * Current * Resistance = I^2*R) and the resistance lowers. The effect is that the in-rush current is limited, and after a second or two the full power is applied to the load.

Google is your friend now. Be safe what ever you do. Consult a sparky if in doubt.

-Tim
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tim_h
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« Reply #20 on: August 03, 2009, 10:38:03 PM »

Pretty sure they were Tridonic, but can't remeber which model.
Just had a look a spec sheet on RS, http://docs-europe.electrocomponents.com/webdocs/04bd/0900766b804bd0a0.pdf   
"-AC Voltage range 198 - 254v
-Undervoltage protection (Shut down) <150V"
Should keep the lights on!

Tim
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daftlad
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« Reply #21 on: August 03, 2009, 11:10:17 PM »

Thanks for that Tim_h
I will get the spec of the one my wholesaler can get tomorrow.
I think we have found something that will work.
I think the problem is the transformer and the cable from it.

Tim w0067814
I am a sparkey and have looked into soft starters, the only commercially available single phase ones i have come accross are not good for starting motors under load. If you know of off the shelf single phase soft starter then let me know.
thanks for everyones help
laters
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ecogeorge
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« Reply #22 on: August 04, 2009, 12:14:42 AM »

QUOTE
It really is the leccy boards problem but they refuse to do anything, I suspect the transformer is too small, it is only 75 meters away and only feeds 4 to 6 properties.
The main fuse is 100 amp, the main problem is if they apply for a bigger supply they will probably end up getting charged for a new transformer?
UNQUOTE
What size supply cables from transformer to fuse board?
rgds George.
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daftlad
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« Reply #23 on: August 04, 2009, 12:19:39 AM »

I think it is 35 mm ali with 25mm copper neutral like co-ax, (i can't remember the name of the cable?) concentric something??
Having been down there today I think there may be a few more houses, but not many.
laters
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tony.
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« Reply #24 on: August 04, 2009, 07:01:17 AM »

split concentric?

what about the farmer digging the track and you supplying the cable, that would leave them to terminate the supply end and load end would save you a lot of cash

tony
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tony.
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« Reply #25 on: August 04, 2009, 07:04:56 AM »

we us abb inverters the acs series , they can start under load for example the last one was for 3 75kw motors for a fan, last week and the other was a water pump 5kw

abb are the db's in my book.

tony
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tim_h
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« Reply #26 on: August 04, 2009, 07:53:06 AM »

I am a sparkey and have looked into soft starters, the only commercially available single phase ones i have come accross are not good for starting motors under load. If you know of off the shelf single phase soft starter then let me know.
thanks for everyones help
laters

For fear of being told off for spamming RS, what about this unit http://docs-europe.electrocomponents.com/webdocs/001b/0900766b8001b8b8.pdf Single phase up to 2.2kW.
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« Reply #27 on: August 04, 2009, 12:17:20 PM »

Tony,
The cables are actually overhead but the leccy board refuse to admit there is anything wrong, so getting them to put new cables in may be a problem, made me think 75 meters of 25mm cable with probably near to 100 amps on it in the winter and then the inrush current of the motor? (i will get my calculator out)
I looked at inverters and took some advice and came to the conclusion that it would be cheaper to put a UPS on the lighting, but now I am not so sure.
Tim
Those soft start units look very intresting, I don't know what to do now, I could change the ballasts in the parlour but then the motors would still affect lighting elsewhere on the farm or i could soft start the motors but there are quite a few motors?
Just spoken to the farmer and we are going to try high frequency ballasts (well try 1 anyway and see how it goes)
Thanks for everyones help,
It's funny how I had an Idea and end up doing something completly different.
laters
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daftlad
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« Reply #28 on: August 13, 2009, 04:57:13 PM »

I just fitted the first phillips high frequency electronic ballast in and it worked a treat Smiley, I started both vacuum pumps at the same time and every light on the farm went out except the one with the new ballast.
Thanks everyone for your help Grin.
laters
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Outtasight
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« Reply #29 on: September 10, 2009, 03:02:43 PM »

As you say the lights are about a 5A load (more when firing up) you should use a ~2kW UPS.

APC make good ones (although you can find cheaper ones).  We use them for servers in our business but there's no reason they wouldn't do what you want.  The APC Smart-UPS 2200VA USB & Serial 230V model will probably do and costs about 570 according to the APC web site.  It may not even run on battery during your voltage sag as it has AVR (a boost-buck converter that will for a short time clip over voltages and boost brown-outs without cutting over to the battery).

It's a simple floor standing thing (they do lots of rack mount ones these days) and can be cold started (i.e. does not have to have mains in order to start so can be used as a standalone power supply).

The batteries are hot swappable and user replaceable (with some cheap makes you have to turn the supply off and even take the thing to bits to get at the batteries).

If the voltage remains low you might end up running on battery all the time it's below the threshold.  The sizing thingy on their web site estimated a big server using about 1300W would run for 10 mins on the batteries.  You can also adjust the voltage sensitivity and battery cut-over set points on this model so that might allow it to just provide cover for when the volts sags for a few seconds but without it latching into battery mode and then it goes dark after 10 minutes as it thinks the voltage is too low to reconnect the mains.

It also has temperature compensated battery charging which will be important as you're using it in a non-air conditioned cow shed rather than a nice comfy computer room...  Just watch out for when it gets cold that it doesn't sit somewhere it will collect condensation and short out internally.
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