About 8 months ago I replaced a burnt out 6 pole lighting contactor 480 volt phot eye controlled(120 v) It fried 2 of 3 20 480 volt breakers. It also trippped a 150 amp 480 volt main. I replaced the breakers and contactor 5 months later it burned out again. The lights(hps 400 watt pole lights) work fine without the contactor. It just burned up again W/in 3 weeks the coils have all been fine but the burning looks like it is on the line side of the contactor. Any ideas???
lighting contactor
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jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: lighting contactor
what was rating of contactors and what is your measured load
what was rating of contactors and what is your measured load
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: lighting contactor
Any chance there is some wiring going bad that causes higher current? Perhaps like when it rains.Your problem seems like it's the load and not the contactors.
Any chance there is some wiring going bad that causes higher current? Perhaps like when it rains.Your problem seems like it's the load and not the contactors.
rcwilson
Senior Member
- Location
- Redmond, WA
Re: lighting contactor
Is it a latched contactor or does the coil need power to hold the contactor in? A voltage dip could be chattering the contacts. Maybe the photocell contact chattters when it picks up the contactor. The arcing contacts are designed to interrupt the ballast current once, not several times in succession as would occur if the contactor is chattering. The arc gases might be building up until the phases flash over.
Is the contactor rated for 277/480V solidly grounded system but it is applied ona 480 V delta or high resistance grounded system?
Good luck.
Is it a latched contactor or does the coil need power to hold the contactor in? A voltage dip could be chattering the contacts. Maybe the photocell contact chattters when it picks up the contactor. The arcing contacts are designed to interrupt the ballast current once, not several times in succession as would occur if the contactor is chattering. The arc gases might be building up until the phases flash over.
Is the contactor rated for 277/480V solidly grounded system but it is applied ona 480 V delta or high resistance grounded system?
Good luck.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: lighting contactor
Do you know the manufacturer and/or model number of the contactor? Is it an Asco 917?
Do you know the manufacturer and/or model number of the contactor? Is it an Asco 917?
loosewire64
Member
Electrical Contractor
Electrical Contractor
I to have an installation with 6-6pole lighting contactors in 2 seperate buildings feeding 400w MH pole lighting. The circuits range from 200' to 800' in overall length. The voltage is 480volt on 2P/20amp circuits with 3 circuits per contactor. The load is not over 12amps per circuit. All contactors are Siemens mechanically held with 2 wire modules controlled via electronic time clocks. There are 128 pole lights most with twin heads. The installation has been online since August 5th 2005. In that time we have had 5 of the 6 contactors fail violently (covers blown off, branch breakers tripped as well as the 200amp main in the site lighting panel tripped). All have failed at different times but only when the circuits are being called for (we might lose 1and 2 months later lose another). We have megged out all wiring and found no issues. We have had little lamp failure (5 lamps total out of 200+) and no ballast failure on this project. I have consulted the Electrical Engineer on the project as well as the manufacturer of both the fixtures and the contactors. All are at a loss as to why this is happening. I have also talked to other engineers and one questioned if we may be getting a capacitor load when the circuits are off due to the length of the circuits. His contention was if a capacitor build up was present when the timeclocks call for lighting there could be an arc flash at the contactor if the contactor is not heavy enough to harness this transient voltage buildup. Has anyone ever heard of this? I have been in this business for 22years performing on 2 to 4 million dollar electrical projects and this has me stumped.
Electrical Contractor
I to have an installation with 6-6pole lighting contactors in 2 seperate buildings feeding 400w MH pole lighting. The circuits range from 200' to 800' in overall length. The voltage is 480volt on 2P/20amp circuits with 3 circuits per contactor. The load is not over 12amps per circuit. All contactors are Siemens mechanically held with 2 wire modules controlled via electronic time clocks. There are 128 pole lights most with twin heads. The installation has been online since August 5th 2005. In that time we have had 5 of the 6 contactors fail violently (covers blown off, branch breakers tripped as well as the 200amp main in the site lighting panel tripped). All have failed at different times but only when the circuits are being called for (we might lose 1and 2 months later lose another). We have megged out all wiring and found no issues. We have had little lamp failure (5 lamps total out of 200+) and no ballast failure on this project. I have consulted the Electrical Engineer on the project as well as the manufacturer of both the fixtures and the contactors. All are at a loss as to why this is happening. I have also talked to other engineers and one questioned if we may be getting a capacitor load when the circuits are off due to the length of the circuits. His contention was if a capacitor build up was present when the timeclocks call for lighting there could be an arc flash at the contactor if the contactor is not heavy enough to harness this transient voltage buildup. Has anyone ever heard of this? I have been in this business for 22years performing on 2 to 4 million dollar electrical projects and this has me stumped.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
While I think this should have started a thread, my thoughts are:
Have any of the replacement contactors failed? In one case all of my failed contactors were taken apart and found to be covered with construction dust. This dust eventuallycaused the contactor mechanisms to bind which prevented them from closing correctly.
In a different case we got a "bad" batch from the factory.
If the capacitance caused by the "long" conductors maintains a large charge overnite (without be disipatted by the ballasts) then who needs UPS batteries.
Have any of the replacement contactors failed? In one case all of my failed contactors were taken apart and found to be covered with construction dust. This dust eventuallycaused the contactor mechanisms to bind which prevented them from closing correctly.
In a different case we got a "bad" batch from the factory.
If the capacitance caused by the "long" conductors maintains a large charge overnite (without be disipatted by the ballasts) then who needs UPS batteries.
loosewire64
Member
We have had 3 replacements fail within 90days of replacement. As far as dust, we have taken all apart and found the contacts to be in good shape except for smoke residue from the flash. Also each time a failure has occurred we have taken the contactor out of the circuit and ran straight off of the breaker for 2 to 8 days while we waited on a replacement. As late as 1-5-07 we replaced 3 of the contactors with SQ D 20amp MH contactors and the operation is very quiet compared to the Siemens. It is to early for me to tell if the SQ D units will solve the issue.
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