Contactors
- Thread starter straps
- Start date
- Status
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Contactors
All contacts actually have three different ratings: Make, Break and Continuous.
"Make" is the amount of current the contacts can handle when they turn something on. Most people know inductive loads, like motors, can have inrush currents of 6-10 times full load amps, but negative temperature co-efficient loads, like halogen lamps can have even higher inrush currents.
"Continuous" is the normal constant current that can be carried. It makes no difference what the load is, amps is amps.
"Break" is the amount of current a contact can turn off. This is probably the most commonly misapplied switch rating because it is often only a fraction of the other two ratings. Horsepower rated devices are rated to break the same amount of current as they can make, this is why their HP rating may be so much lower than their continuous current rating.
All contacts actually have three different ratings: Make, Break and Continuous.
"Make" is the amount of current the contacts can handle when they turn something on. Most people know inductive loads, like motors, can have inrush currents of 6-10 times full load amps, but negative temperature co-efficient loads, like halogen lamps can have even higher inrush currents.
"Continuous" is the normal constant current that can be carried. It makes no difference what the load is, amps is amps.
"Break" is the amount of current a contact can turn off. This is probably the most commonly misapplied switch rating because it is often only a fraction of the other two ratings. Horsepower rated devices are rated to break the same amount of current as they can make, this is why their HP rating may be so much lower than their continuous current rating.
Re: Contactors
Conservatively, I would tell you to use the inductive if you have a lot of Metal Hallide or Flourescent lighting. The ballasts tend to have quite a bit of inrush current. Also, the more oversized a contactor is, the longer the contacts tend to last, so if it's financially doable, going one size higher is not a bad thing.
Conservatively, I would tell you to use the inductive if you have a lot of Metal Hallide or Flourescent lighting. The ballasts tend to have quite a bit of inrush current. Also, the more oversized a contactor is, the longer the contacts tend to last, so if it's financially doable, going one size higher is not a bad thing.
Re: Contactors
Got stupid again bought 4 new 40 amp resistive contactors to use on the roof top lighting and same old crap 3 out of four failed then it started in all mounted in a 12 x 12 x 6 pvc box.First one failed then another disconnected feeds from timer and isolated it down to 1 contactor at a time. Same old crap damn supply house selling junk. Never again will I buy a non-name brand contactor it is way too much time wasteing with non name brands. CES yuk on your contactors
Got stupid again bought 4 new 40 amp resistive contactors to use on the roof top lighting and same old crap 3 out of four failed then it started in all mounted in a 12 x 12 x 6 pvc box.First one failed then another disconnected feeds from timer and isolated it down to 1 contactor at a time. Same old crap damn supply house selling junk. Never again will I buy a non-name brand contactor it is way too much time wasteing with non name brands. CES yuk on your contactors
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Contactors
Just goes to prove "You don't get what you don't pay for".
Just goes to prove "You don't get what you don't pay for".
Re: Contactors
physis, Good point. Sometimes one can't see the forest for trees.
Contact failure can be caused by the control circuit. If the control causes the coil to be energized inconsistently that may cause the contacts to chatter, the arcing causes the contact surface to melt and puddle which may end up welding the contacts together of just plain destroying the contacts.
I had this issue come up with a refrigeration system where the contacts of a contactor were failing. When I asked the technician to check the control circuit he located a contact of a refrigerant line that was failing. The pressure switch contacts had corroded due to a refrigerant leak at that point which then caused an inconsistent control voltage applied to the contactors coil causing the contactor to chatter.
physis, Good point. Sometimes one can't see the forest for trees.
Contact failure can be caused by the control circuit. If the control causes the coil to be energized inconsistently that may cause the contacts to chatter, the arcing causes the contact surface to melt and puddle which may end up welding the contacts together of just plain destroying the contacts.
I had this issue come up with a refrigeration system where the contacts of a contactor were failing. When I asked the technician to check the control circuit he located a contact of a refrigerant line that was failing. The pressure switch contacts had corroded due to a refrigerant leak at that point which then caused an inconsistent control voltage applied to the contactors coil causing the contactor to chatter.
Re: Contactors
there are 3 contactors in a 12 x 12x 6 inch PVC box with the cover off. We wired them all from 1 Timer T101 with jumpers from the lines and jumpers from the neutrals. Also tried them in a metal box .next attempt will be to attach a bonding wire to each mount.
In the 12 x 12 box I have a strip of neutral studs and a 16 screw strip of neutrals all isolated from each other ran a #6 green to main panel and did the same for the neutrals. Less wire less heat. They failed within 5 seconds of being activated not all just some then it started jumping around so I isolated 1 contactor with 1 set of lines and loads. Same old problem they fail right away .All are rated at 30 amps resistive. With cbs rated at 20 amp with 12 awg wire. First stop tomoroow check on graingers screw the cost I am sick of junk materials Back to square d.
.
[ December 27, 2005, 12:22 AM: Message edited by: straps ]
there are 3 contactors in a 12 x 12x 6 inch PVC box with the cover off. We wired them all from 1 Timer T101 with jumpers from the lines and jumpers from the neutrals. Also tried them in a metal box .next attempt will be to attach a bonding wire to each mount.
In the 12 x 12 box I have a strip of neutral studs and a 16 screw strip of neutrals all isolated from each other ran a #6 green to main panel and did the same for the neutrals. Less wire less heat. They failed within 5 seconds of being activated not all just some then it started jumping around so I isolated 1 contactor with 1 set of lines and loads. Same old problem they fail right away .All are rated at 30 amps resistive. With cbs rated at 20 amp with 12 awg wire. First stop tomoroow check on graingers screw the cost I am sick of junk materials Back to square d.
.
[ December 27, 2005, 12:22 AM: Message edited by: straps ]
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
Re: Contactors
This is too complex, for me, without a digital-camera picture posted here.
My loads are strictly lighting with maybe 1 4 or 5 amp mini motor 99 percent lighting
My wall mounted pool-motor timer controls up to 20 amps, why can't you use a timer like this or larger for your loads?
This is too complex, for me, without a digital-camera picture posted here.
My loads are strictly lighting with maybe 1 4 or 5 amp mini motor 99 percent lighting
My wall mounted pool-motor timer controls up to 20 amps, why can't you use a timer like this or larger for your loads?
Re: Contactors
Straps,
From what I see we're still shooting at shadows.
It is of my opinion that you have a control voltage problem but still have omitted information that would define it.
1) What is the size of the contactor and the coil volts, pull-up VA, and seal-in VA are.
2) Are you pulling in all of the contactors at the same time?
3) What is the VA of your power source for the coils?
The coils should pull-in and seal with about 70-75% of the rated voltage. Should the pull-in VA of all of the coils combined cause the control voltage to drop below the allowable pull-in voltage the contacts will not be pulled together securely and cuase them to arc and fail.
Check the manufacturers specs and also check to assure that you have a contol power source that is stiff enough to maintain the voltage level needed to pull in the pull in the coils.
Straps,
From what I see we're still shooting at shadows.
It is of my opinion that you have a control voltage problem but still have omitted information that would define it.
1) What is the size of the contactor and the coil volts, pull-up VA, and seal-in VA are.
2) Are you pulling in all of the contactors at the same time?
3) What is the VA of your power source for the coils?
The coils should pull-in and seal with about 70-75% of the rated voltage. Should the pull-in VA of all of the coils combined cause the control voltage to drop below the allowable pull-in voltage the contacts will not be pulled together securely and cuase them to arc and fail.
Check the manufacturers specs and also check to assure that you have a contol power source that is stiff enough to maintain the voltage level needed to pull in the pull in the coils.
Re: Contactors
What is complex about this their is a total of 4 each 3 pole contactors in a pvc box measureing 12 inchs by 12 inchs by 6 inchs deep. With no cover on it with ni load attached to the 4 brand new contactors they failed as soon as power was applied to the coils they are the correct voltage,amperage and so forth they are just junk.
It does not seem to matter the actuating voltage comes from a plain simple T101 timer. We have used this same setup in 5 other locations on the church campus without too much problem.
As far as square d tomorrow I am gonna go buy square d cause these brand xs are garbadge pure and simple they have sold us a total of 12 contactors to date 4 have failed right away or withing 5 seconds. I have tried to attach bonding wires no help. I have also recycled the t101 timer at least 5 times and eventually they stop humming but if shut off then turned back on they start humming again.
I think I am being sold junk with a capital j. These are manufactured by some subsidary of CES
What is complex about this their is a total of 4 each 3 pole contactors in a pvc box measureing 12 inchs by 12 inchs by 6 inchs deep. With no cover on it with ni load attached to the 4 brand new contactors they failed as soon as power was applied to the coils they are the correct voltage,amperage and so forth they are just junk.
It does not seem to matter the actuating voltage comes from a plain simple T101 timer. We have used this same setup in 5 other locations on the church campus without too much problem.
As far as square d tomorrow I am gonna go buy square d cause these brand xs are garbadge pure and simple they have sold us a total of 12 contactors to date 4 have failed right away or withing 5 seconds. I have tried to attach bonding wires no help. I have also recycled the t101 timer at least 5 times and eventually they stop humming but if shut off then turned back on they start humming again.
I think I am being sold junk with a capital j. These are manufactured by some subsidary of CES
Awg-Dawg
Senior Member
- Location
- Dayton Ohio
Re: Contactors
Originally posted by straps:
It does not seem to matter the actuating voltage comes from a plain simple T101 timer.
Is that where the neutral comes from also? You might want to check to make sure that is in fact a neutral.(to the coil)
Originally posted by straps:
It does not seem to matter the actuating voltage comes from a plain simple T101 timer.
Is that where the neutral comes from also? You might want to check to make sure that is in fact a neutral.(to the coil)
Re: Contactors
From an application engineer's standpoint none of the questions I had asked previously were answered.
It is not all that unusual that technicians just replace failed parts and complain about what "junk" they are. If the contactors are IEC there are extremely application sesitive and, when replaced with NEMA which can withstand more abuse the problem may go away.
It does take some effort to find out what the "PULL-UP" va and minimuim "PULL-IN" voltage is. It also takes so effort to verify what the control va is.
I reread Strapps replys which did not appear to verify if there is even enough va to pull in the coils of the contactors which I assume are being all pulled in at the same time.
Also, are the contacts of the T101 relay able to carry that current?
If I were the distributor I certainly would want some facts with regard to the installation to determine if there is a misapplication.
From an application engineer's standpoint none of the questions I had asked previously were answered.
It is not all that unusual that technicians just replace failed parts and complain about what "junk" they are. If the contactors are IEC there are extremely application sesitive and, when replaced with NEMA which can withstand more abuse the problem may go away.
It does take some effort to find out what the "PULL-UP" va and minimuim "PULL-IN" voltage is. It also takes so effort to verify what the control va is.
I reread Strapps replys which did not appear to verify if there is even enough va to pull in the coils of the contactors which I assume are being all pulled in at the same time.
Also, are the contacts of the T101 relay able to carry that current?
If I were the distributor I certainly would want some facts with regard to the installation to determine if there is a misapplication.
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