Electrician Talk banner
1 - 20 of 38 Posts

·
Registered
Joined
·
1,287 Posts
Discussion Starter · #1 ·
Ok this will be the 3rd contactor I've had to replace for a jockey pump controller. The jockey pump is 120 volt. Here's how it works, the pressure switch calls for pump, which kicks contactor on, but runs no more than a second, if even, that's how quick it gets the pressure back to set point. On certain days this pump is called on several times depending on temperature conditions, but at least works once or twice a day. My thoughts are that it is too harsh on the contactor who roughly only sees LRA of motor when called upon. I'm looking for any guidance or thoughts guys! I don't want to mess with pressure switch deadband range. Is there a soft starter or something for a 120 volt motor? Please help. I'm gonna get on my phone and upload photos.
 

·
Registered
Joined
·
782 Posts
1.I assume the control wire from pressure switch goes directly to the contactor coil without passing through a fuse that's why your contactor coil keeps burning
that's where I would start because from the circuit I cant see that's provision
Sent from my HUAWEI Y210-0100 using Tapatalk 2
 

·
Registered
Joined
·
1,287 Posts
Discussion Starter · #8 ·
1.I assume the control wire from pressure switch goes directly to the contactor coil without passing through a fuse that's why your contactor coil keeps burning
that's where I would start because from the circuit I cant see that's provision
Sent from my HUAWEI Y210-0100 using Tapatalk 2
The coil is not what's burning up, it is the contacts themselves.
 

·
Registered
Joined
·
782 Posts
what's the rating of your contactor?

Sent from my HUAWEI Y210-0100 using Tapatalk 2
 

·
Registered
Joined
·
4,664 Posts
GEORGE D said:
.....which kicks contactor on, but runs no more than a second, if even, that's how quick it gets the pressure back to set point. On certain days this pump is called on several times depending on temperature conditions, but at least works once or twice a day. My thoughts are that it is too harsh on the contactor who roughly only sees LRA of motor when called upon.....

George, as Jraef will probably soon point out, the problem lies in the extremely short duty cycle being repeated many times each day. You can keep changing contactors 'till you're blue in the face and they will keep burning out the contacts. (Oh and the motor will soon follow.)

The ONLY solution to the problem is to get the plumber or whoever spec'd this to change the pressure switch settings to allow a longer run time and less cycling. (I.E. higher operating pressure.)

THEN replace the contactor for the last time.

Actually, I wonder what idiot spec'd a jockey pump on a system where the pressure is so high that it only needs to cycle for such a short time anyways....:whistling2::no:

8V71, paralleling the contacts won't help at all..it will just arc even more.

Nickson, increasing the rating won't help either for the reasons I explained above. Good thinking though...in any other case your idea would work.
 

·
Registered
Joined
·
782 Posts
The coil is not what's burning up, it is the contacts themselves.
what's the rating of your contactor then

Sent from my HUAWEI Y210-0100 using Tapatalk 2
 

·
Registered
Joined
·
1,082 Posts
how about doubling the size of the contactor? looks like you have plenty of room.like the others have said , need a longer cycle time too.:eek: also what is a jockey pump?:eek:
 

·
Master Of Disaster
Generator installs and service , temp and emergency power
Joined
·
1,777 Posts
Install control trans and run 24 volt thru the pres switch and contactor

That's how we set up well pumps and air comps
 

·
Donuts > Fried Eggs
Joined
·
17,042 Posts
There's nothing about a few operations per day that would suggest an excessive duty cycle, I've installed appropriately sized contactors that operated dozens of times per day and have for years.

My guess is the pressure switch isn't providing solid control power and you're getting chattering, which definitely would be unusually hard on the contacts. The solution might be to install a timing relay with a very short off-delay, so that if the pressure control is causing an intermittent, it isn't transmitted to the contactor coil.
 

·
Registered
Joined
·
1,212 Posts
What pressure,s are you dealing with? I'm not familiar with a jockey pump. On/off pressure? Add a badder tank for a reserve of water, would give longer run time between cycles, same idea as water pump system for your home.
 

·
Registered
Joined
·
1,287 Posts
Discussion Starter · #18 ·
There's nothing about a few operations per day that would suggest an excessive duty cycle, I've installed appropriately sized contactors that operated dozens of times per day and have for years.

My guess is the pressure switch isn't providing solid control power and you're getting chattering, which definitely would be unusually hard on the contacts. The solution might be to install a timing relay with a very short off-delay, so that if the pressure control is causing an intermittent, it isn't transmitted to the contactor coil.
My biggest concern is changing the design and being held accountable if/when sh!t hits the fan. I'm thinking it is harsh on the contractors, considering the short duration of run, which means the contacts are forced apart at higher load. I started a thread a while about this same jockey pump and how I thought it might be the pressure switch. Today is when I realized how short of time the motor actually runs. There's still a chance the pressure switch is faulty; I plan on changing it just to be safe.
 

·
Donuts > Fried Eggs
Joined
·
17,042 Posts
Just out of curiosity, how do you know this thing only runs a couple times a day? How is it that the pressure bleeds down that slowly, but is still rebuilt within a matter of seconds, is the motor really that oversized?

Have you checked to see if you have a bad expansion tank and this is actually cycling many times per hour?
 

·
Registered
Joined
·
1,212 Posts
Big John said:
Just out of curiosity, how do you know this thing only runs a couple times a day? How is pressure bled down that slowly, but still rebuilt within a matter of seconds? Have you checked to see if you have a bad expansion tank and this is actually cycling many times per hour?
If there is a expansion tank on the system , big john is absolutely correct.
Same thing happens to well pumps when tank pukes.
 
1 - 20 of 38 Posts
Top