Metal Halide lighting problem

[amdx]

Hi All,
I have a friend that has a Tuna boat, he uses two Metal Halide lights to
light up the deck. The boat has a 3 phase generator onboard.
This drives a large freezer compressor and an air compressor. When one of
the compressors comes on the lights go out, need to cool and the refire.
The lights are single phase 240 volt units.
What can be done to keep the lights working during compressor startup?
Would a constant voltage transformer such as this help?
http://cgi.ebay.com/EK-1352-SOLA-CO...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
Mike

 

[Ecnerwal]

First cover the possibility that the present wiring is done all wrong -
ie, are the lights and other single-phase loads all piled on one phase,
or are single-phase loads distributed across phases sensibly? Is the
generator just plain too small and needs to be upgraded? Are there
capacitors on the compressor motors that might be bad, or should there
be capacitors, but there are not? Certainly for the air compressor, an
unloader valve would be a good thing, if there is not one on it (or it's
not working right if there is) already.

 

[amdx]

Cut over to incandescents!

John

That is one of the captain's ideas.
Mike

 

[Jamie]

Hi All,
I have a friend that has a Tuna boat, he uses two Metal Halide lights to
light up the deck. The boat has a 3 phase generator onboard.
This drives a large freezer compressor and an air compressor. When one of
the compressors comes on the lights go out, need to cool and the refire.
The lights are single phase 240 volt units.
What can be done to keep the lights working during compressor startup?
Would a constant voltage transformer such as this help?
http://cgi.ebay.com/EK-1352-SOLA-CO...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
Mike

Use different lights and a separate generator for them.


http://webpages.charter.net/jamie_5"

 

[Jon Slaughter]

Hi All,
I have a friend that has a Tuna boat, he uses two Metal Halide lights to
light up the deck. The boat has a 3 phase generator onboard.
This drives a large freezer compressor and an air compressor. When one of
the compressors comes on the lights go out, need to cool and the refire.
The lights are single phase 240 volt units.
What can be done to keep the lights working during compressor startup?
Would a constant voltage transformer such as this help?
http://cgi.ebay.com/EK-1352-SOLA-CO...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
Mike

No, probably not.

If the compressor doesnt come on too often then how bout a UPS system? Might
be a cheaper solution and provide enough juice to keep the lights on. The
problem is that the compressor might suck the juice from the ups too but
what you can do here when the compressor turns on it cuts the power to the
ups for a few sceonds. The ups will supply current to the lights and then be
connected back.

If metal halides can be run with DC then simply using a power supply will
work. Large enough caps to keep a temporary supply. In fact what you would
want is to charge the caps before the compressor came on, disconnect ac from
lights and connect cap then switch back. This way the cap is only on for
charging and not wasting power(Although probably not an issue) and the
light's are not running off dc for too long. This might be the easiest and
cheapest solution if it worked.

You can try other things too like batteries to an inverter but basically
your creating a UPS system. Of course you can replace the lights or get a
more powerful generator.

 

[Spehro Pefhany]

No, probably not.

If the compressor doesnt come on too often then how bout a UPS system? Might
be a cheaper solution and provide enough juice to keep the lights on. The
problem is that the compressor might suck the juice from the ups too but
what you can do here when the compressor turns on it cuts the power to the
ups for a few sceonds. The ups will supply current to the lights and then be
connected back.

Good idea, but you don't try to run the compressor off the UPS. It
gets wired directlyh off the generator. The UPS is just for the
lights. Assuming we're talking about something like a couple of 400W
metal halide lights, a 1500VA UPS should be okay. Here's one for $200:

http://www.upsforless.com/powercomb...lmodel220-240vtowerupsnewbnt-1500ap-220v.aspx

Best regards,
Spehro Pefhany

 

[Jon Slaughter]

Good idea, but you don't try to run the compressor off the UPS. It
gets wired directlyh off the generator. The UPS is just for the
lights. Assuming we're talking about something like a couple of 400W
metal halide lights, a 1500VA UPS should be okay. Here's one for $200:

http://www.upsforless.com/powercomb...lmodel220-240vtowerupsnewbnt-1500ap-220v.aspx

of course

That is the problem I tried to discribe which is why you might have to
temporarily disconnect it from the generator while the compressor is turning
on. I suppose one would simply have to test for this or by a larger ups or
get more of them.

 

[[email protected]]

Hi All,
I have a friend that has a Tuna boat, he uses two Metal Halide lights to
light up the deck. The boat has a 3 phase generator onboard.
This drives a large freezer compressor and an air compressor. When one of
the compressors comes on the lights go out, need to cool and the refire.
The lights are single phase 240 volt units.
 What can be done to keep the lights working during compressor startup?
Would a constant voltage transformer such as this help?http://cgi.ebay.com/EK-1352-SOLA-CO.....66:2|65:12|39:1|240:1318|301:1|293:1|294:50
                                                    Mike

so you probably figured that the voltage is dropping too much when the
compressors kicks in and the lights can't continue through the voltage
dip

1) check that the lights and comps are wired to the generator with
seperate wires, you don't want them to share any long calbes that
would make the voltage drop worse than it is. The generator will drop
some but extra shared wiring will make it worse..

2) Some compressors can be started with an unloader, which is a valve
that releases the back pressure...

3) Add a few incandescent lights to the light system so that when the
MH lights need to re-strike but in the meantime you have enough light
to work with...

A UPS for the MH lights is an obvious answer but if they are big
lights that may be very heavy and expensive..

good luck
Mark

 

[Spehro Pefhany]

of course

That is the problem I tried to discribe which is why you might have to
temporarily disconnect it from the generator while the compressor is turning
on. I suppose one would simply have to test for this or by a larger ups or
get more of them.

I would submit that a UPS that does not operate properly when the
input voltage sags is not really a UPS.


Best regards,
Spehro Pefhany

 

[Jon Slaughter]

I would submit that a UPS that does not operate properly when the
input voltage sags is not really a UPS.

Well, as you well know it could only take so much. If the compressor draws
enough juice it could cause it to sag. I guess the only way would be to test
it out... not a big deal and not a big deal if it does need to be
temporarily disconnected.

 

[Spehro Pefhany]

Well, as you well know it could only take so much. If the compressor draws
enough juice it could cause it to sag. I guess the only way would be to test
it out... not a big deal and not a big deal if it does need to be
temporarily disconnected.

It *is* sagging-- that's what's killing the arcs in the metal halide
bulbs. And it's not good for them-- they should be allowed to cool
fully before restarting.

And the whole POINT of a UPS is to maintain quality power on the
output if the input drops below nominal.



Best regards,
Spehro Pefhany

 

[Martin Brown]

Hi All,
I have a friend that has a Tuna boat, he uses two Metal Halide lights to
light up the deck. The boat has a 3 phase generator onboard.
This drives a large freezer compressor and an air compressor. When one of
the compressors comes on the lights go out, need to cool and the refire.

One possible solution not mentioned yet is to replace the MH lamps with
ones that are capable of nominally instant restrike. They take more like
2-3 minutes to recover from arc failure back to a useful brightness
rather than the 10 minutes on traditional lamps and ballasts. eg.

http://www.venturelighting.com/TechCenter/Uni-Form-Tech-Benefits.html

No idea how they would shape up in a maritime environment with salt
spray etc. And they are obviously more expensive.

The lights are single phase 240 volt units.
What can be done to keep the lights working during compressor startup?

Check the wiring. Put a simple filament lamp in parallel so you don't
lose all lighting for an extended period?

Would a constant voltage transformer such as this help?
http://cgi.ebay.com/EK-1352-SOLA-CO...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
Mike

Probably not. A suitably rated UPS between the lamps and the generator
might help. Presumably the power only dips for a few seconds when the
compressor is pulling its peak maximum starting current.

Regards,
Martin Brown

 

[amdx]

Good idea, but you don't try to run the compressor off the UPS. It
gets wired directlyh off the generator. The UPS is just for the
lights. Assuming we're talking about something like a couple of 400W
metal halide lights, a 1500VA UPS should be okay. Here's one for $200:

http://www.upsforless.com/powercomb...lmodel220-240vtowerupsnewbnt-1500ap-220v.aspx


Best regards,
Spehro Pefhany

The captain did mention a UPS, he has one for his computer and wondered
whether
one would work on the lights.
Looks like I should make sure the wiring is configured to eliminate as
much voltage
drop to the lights as possible. If that doesn't help then look into a UPS,
different lights,
or auxiliary lights during the cooling and refire time.

These lights have voltage taps on them like 208V, 220V, 230, 240V. I don't
know
where they are set, but is there a scenario where one tap would be prefered
to help
keep the lights on during the brownout?
Mike

 

[Spehro Pefhany]

The captain did mention a UPS, he has one for his computer and wondered
whether
one would work on the lights.
Looks like I should make sure the wiring is configured to eliminate as
much voltage
drop to the lights as possible. If that doesn't help then look into a UPS,
different lights,
or auxiliary lights during the cooling and refire time.

These lights have voltage taps on them like 208V, 220V, 230, 240V. I don't
know
where they are set, but is there a scenario where one tap would be prefered
to help
keep the lights on during the brownout?
Mike

Probably not-- without compromising things during normal operating
conditions.



Best regards,
Spehro Pefhany

 

[Jon Slaughter]

Depends on how the ups works. If it's simply hooked up parallel to the other
power source then it too can sag. All depends on the compliances. I'm no
expert but I guess they just use batteries and an inverter. The batteries
can only put out so much surge current(although I imagine it is pretty
decent for lead acid). This still might not be enough as the compressor
might "steal" it too. It's only a hypothetical and I pointed it out just in
case.

 

[Jon Slaughter]

The captain did mention a UPS, he has one for his computer and wondered
whether
one would work on the lights.
Looks like I should make sure the wiring is configured to eliminate as
much voltage
drop to the lights as possible. If that doesn't help then look into a UPS,
different lights,
or auxiliary lights during the cooling and refire time.

These lights have voltage taps on them like 208V, 220V, 230, 240V. I
don't know
where they are set, but is there a scenario where one tap would be
prefered to help
keep the lights on during the brownout?
Mike

The problem is simply that the voltage is drooping because of the large
surge current when the compressor comes on. Similar things happen, say, when
peoples AC comes on and the lights dim. You gotta regulate the voltage
somehow. I'm sure there are many ways but it all depends on how much
regulation you need.

Your power source, the generator, can output only so much current. The
compressor is a load as it the lights. When the compressor comes on it
"overloads" the generator. Basically because the compressor is "asking" for
much more current than the generator can output the generator drops it's
voltage to compensate(since the compressor draws less current with less
voltage).

The problem here is that when the generator drops it's voltage it it no
longer supplies the correct voltage to the lights which they need to run.
(which is different than the compressor which is mainly current driven)

What this basically means is that your generator is not big enough. Get a
bigger one or supplement it.

Usually DC motors have a start capacitor to supply that extra juice:
http://en.wikipedia.org/wiki/Motor_capacitor

And AC motors can use a similar feature but that it works in a different
way(offsetting the current at startup to reduce the surge)
http://www.pentairwater.com/pentekmotors/Assets/P8098TB_SMC_CSIR.pdf

 

[amdx]

I would submit that a UPS that does not operate properly when the
input voltage sags is not really a UPS.


Best regards,
Spehro Pefhany

I had another talk with the captain,
The lights are 1000w each so the UPS suggested is to small to run one light.
Sometimes only one light goes out, so maybe the voltage is very close to the
point where the light would stay lit during the sag.
The generator is a 30KW 3 phase unit.
The freezer compressor is a 7.5hp 3 phase unit.
Voltage normally runs at about 219 volts.
The air compressor is not a concern (only used to power main motor starter)
normally off.
The 3 phase circuit breaker box has a breaker that supplies 2 phase to a
second circuit breaker box.
The second breaker box supplies two 1000watt lights on a single 10 gauge
cable.
Captain said the lights have taps at 110v, 220v, 240v, and 277v.
They are now using the 240 volt tap.
Here is a generic schematic of a metal halide light, I found.
http://www.venturelighting.com/images/Wiring_G_big.gif
I'm figuring he's running the lights at a low voltage with the 240v tap and
a 219V supply.
Is that correct?
If so, I'm going to suggest adjusting to the 220v tap.
Then try disconnecting one of the lights and running just one light on the
single 10 gauge wire.
Maybe the combination of the two will be enough to keep the lights lit.
Mike

 

[Ecnerwal]

I'm figuring he's running the lights at a low voltage with the 240v tap and
a 219V supply.
Is that correct?
If so, I'm going to suggest adjusting to the 220v tap.

Yup, if the voltage readings are accurate, that will probably do it. Try
just that, first.

 

[Adrian Tuddenham]

Hi All,
I have a friend that has a Tuna boat, he uses two Metal Halide lights to
light up the deck.

Far too risky. Any glitch (not just due to the compressor) could plunge
the deck into prolonged darkness at any time. He ought to consider
fitting a different system altogether - or at least some sort of
battery-operated emergency lighting..

 

[Adrian Tuddenham]

Or put in a compressor that has a start-up pressure bypass.

That won't stop a dangerous situation arising if there is the slightlest
glitch in the supply from any other cause, or if someone accidentally
switches the lamps off for a moment.

I've seen a similar situation in a village hall that was lit by high
pressure discharge lamps. We kept the switch on one circuit taped-over
in the 'off' position, so that we always had one cold lamp ready for a
quick re-start.