# Jockey Pump Contactor Failure



## GEORGE D (Apr 2, 2009)




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## 8V71 (Dec 23, 2011)

Have you ever tried jumping all of the unused contacts together?


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## GEORGE D (Apr 2, 2009)

8V71 said:


> Have you ever tried jumping all of the unused contacts together?


Not sure what you mean, there are no unused contacts, they're being used as part of the control circuitry.


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## 8V71 (Dec 23, 2011)

OK...

Could you add another 3 or 4 pole contactor?


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## GEORGE D (Apr 2, 2009)

8V71 said:


> OK...
> 
> Could you add another 3 or 4 pole contactor?


Possibly. I'm not really understanding why?


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## Safari (Jul 9, 2013)

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


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## GEORGE D (Apr 2, 2009)

nickson said:


> 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.


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## Safari (Jul 9, 2013)

what's the rating of your contactor?

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## guest (Feb 21, 2009)

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.


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## Safari (Jul 9, 2013)

GEORGE D said:


> The coil is not what's burning up, it is the contacts themselves.


what's the rating of your contactor then

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## circuitman1 (Mar 14, 2013)

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. also what is a jockey pump?


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## A Little Short (Nov 11, 2010)

circuitman1 said:


> also what is a jockey pump?


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## Safari (Jul 9, 2013)

A Little Short said:


>


thats funny, hey I also dnt know what is a jockey pump 

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## socalelect (Nov 14, 2011)

Install control trans and run 24 volt thru the pres switch and contactor 

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


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## Big John (May 23, 2010)

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.


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## Hmacanada (Jan 16, 2014)

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.


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## GEORGE D (Apr 2, 2009)

Big John said:


> 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.


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## Big John (May 23, 2010)

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?


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## Hmacanada (Jan 16, 2014)

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.


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## GEORGE D (Apr 2, 2009)

Ok, now you guys may be on to something, this is where my absolute lack of fire systems comes into play. I took a video of it, the starter that is, under a test where I released pressure to see it in action, just not sure how to post it besides YouTube? Can you guys elaborate on the tank theory? Thanks


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## Hmacanada (Jan 16, 2014)

Some where in the system should be a expansion tank as john said. It's job is to trap air in the system as the pump builds pressure it compresses the air . Then if it calls for water the air forces the water back into the system until it drops to the on pressure. With out it you "dead head" the pump . You can't compress water, that's why the 1 second run time.


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## Big John (May 23, 2010)

The idea I was thinking was that in a system with a lot of outflow you put an expansion tank in that holds pressure and allows it to be bled down slowly as flow increases. This keeps the pump from having to accommodate the immediate pressure drop that would occur without the tank. If the tank is bad and fills with water, then the pump short-cycles.

But, I didn't realize this was fire-sprinkler system. While it's apparently still possible to have expansion tanks in fire sprinklers, I've never seen one. What is very common though is for fire sprinkler jockey pumps to short-cycle like you're describing, because they are pumping into what ideally should be a totally closed system with no leaks.

I also agree that if this is a fire sprinkler system, I'd be very hesitant to modify any controls. I'd be interested to hear _mxslick's_ thinking on why you can't parallel or series the contacts to reduce the arcing, because I honestly think that would help.


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## Hmacanada (Jan 16, 2014)

Look up expansion tanks on sprinkler systems, pretty much a must due to temperature change in the building the water itself will expand and contract . It needs a place to do that . Steel pipe won't allow it to happen without splitting something.


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## guest (Feb 21, 2009)

Big John said:


> The idea I was thinking was that in a system with a lot of outflow you put an expansion tank in that holds pressure and allows it to be bled down slowly as flow increases. This keeps the pump from having to accommodate the immediate pressure drop that would occur without the tank. If the tank is bad and fills with water, then the pump short-cycles.
> 
> But, I didn't realize this was fire-sprinkler system. While it's apparently still possible to have expansion tanks in fire sprinklers, I've never seen one. What is very common though is for fire sprinkler jockey pumps to short-cycle like you're describing, because they are pumping into what ideally should be a totally closed system with no leaks.
> 
> I also agree that if this is a fire sprinkler system, I'd be very hesitant to modify any controls. _* I'd be interested to hear mxslick's thinking on why you can't parallel or series the contacts to reduce the arcing, because I honestly think that would help.*_


To answer your question, the reason parallel contacts (usually) do not work as expected and arc more rather than less is this: each set of contacts in a contactor (or relay) do not close (or break) at the EXACT same time. And the delay between contact sets is not constant either. So instead of one arc per phase/leg, you now have multiple arcs happening on each phase/leg. It only takes 1/120 of a second difference between sets for the contact's action to be "out of step" with the others. 

And contact resistances will vary which will result in uneven distribution of current...which gets worse as the contacts erode from the arcing. Which creates more arcing over time...a vicious cycle that ends when the contacts burn up altogether. 

The above explanation was given to me by both an old-school motor shop guy and one of the contactor makers some years ago. (Because I tried the parallel contact trick and only succeeded in burning up 3 contactors before I was told this.  )

As for series contact connections, the problem there is still one of timing as one set in the series string will ultimately be the last to open (or close) so the full load is still only being "seen" by that one set of contacts.


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## Big John (May 23, 2010)

I dunno. Large breakers all have multiple independently spring loaded contact assemblies that all have to carry a portion of the current. It doesn't decrease their current-carrying ability, quite the opposite: The higher the ampacity, the more contacts a breaker will have. 

That said, one work-around would be to put all three poles in series instead of parallel. Each contact would still see the same current, but you'd have triple the air-gap and the arc would extinguish much more rapidly and cause less heating and less contact erosion.


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## oliquir (Jan 13, 2011)

euh pretty simple just use a solid state relay for motor, it is just a 120v motor, you dont even need a contactor since you have only one pole to switch


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## GEORGE D (Apr 2, 2009)

oliquir said:


> euh pretty simple just use a solid state relay for motor, it is just a 120v motor, you dont even need a contactor since you have only one pole to switch


Any reason this can't be used?


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## Hmacanada (Jan 16, 2014)

IMO it might be better, but still going to prematurely fail because of the jogging the motor is doing.
Look into plumber for expansion tank as I said in other posts.
Just my opinion man.
There is more to this then a cheap contactor problem.


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## sparkywannabee (Jan 29, 2013)

All that motor does is turn a pump to maintain certain minimum pressure, right. On a leak free system that motor should not have to come on for days, maybe weeks. Have you walked around checking for leaks.


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## Big John (May 23, 2010)

GEORGE D said:


> Any reason this can't be used?


 Might be a fine solution. All I can say is I've never seen the need for it, because I've never heard of this problem on a properly sized, properly working contactor. 

My only concern would be that if you are getting control circuit intermittents, a SSR will switch fast enough that it passes 100% of them on to the motor. 

What's the FLA on this motor, and have all the previous contactors been the same model?


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## Jlarson (Jun 28, 2009)

The contacts should already be jumped together so the MMS doesn't trip on phase loss. 

Have a fire alarm company come out and check the system, proper pressures, look for leaks, check for excess air and check any air release valves.


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## GEORGE D (Apr 2, 2009)

Jlarson said:


> The contacts should already be jumped together so the MMS doesn't trip on phase loss.
> 
> Have a fire alarm company come out and check the system, proper pressures, look for leaks, check for excess air and check any air release valves.


Just wanted to point out that is 120 volt motor, so no phase loss issues. However, I will get them to have fire alarm guys give it a check prior to moving forward. Thanks for everyone's input!


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## Jlarson (Jun 28, 2009)

GEORGE D said:


> Just wanted to point out that is 120 volt motor, so no phase loss issues. However, I will get them to have fire alarm guys give it a check prior to moving forward. Thanks for everyone's input!


Yeah but when you use a 3 pole mms or a electronic OL on a single phase load you have to jump through the unused contacts so it senses current on all three poles.


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## JRaef (Mar 23, 2009)

NFPA 20 governs the use and setting of controls used in Fire Pump Systems. Although the Jockey Pump is not as critical in terms of the FIRE, it is critical to the SYSTEM, because it compensates for leaks and temperature changes. So I don't think you can mess with how it is set up without consulting whomever is responsible for testing and maintaining the fire pump system.

That said, there is typically (in my experience) a 15 psi differential on the Jockey Pump pressure switch. If yours is chattering in and out really fast like this, that is indicative of either a setting done incorrectly in that switch, or a malfunction in the switch or a leak. I would find out who is responsible for maintaining that fire suppression system, usually a contractor who specializes in it, and alert them to the fact that the starter is banging on and off too rapidly. It might be an symptom of a serious leak.

Side note: The issue of not using parallel contacts to switch motors is based on using multiple single pole contactors on a 3 phase motor. Parallel (bridged) contacts are used all the time to increase the current carrying capacity of contactors. Most mfrs sell a bridging adapter specifically for that purpose. Here is what the one looks like for that Siemens contactor shown;









It puts all 3 power contacts in parallel and gives you one terminal block. The total current through the three contacts is de-rated a little so it's not quite 3x the single pole rating, but it is maybe 2.9x. Won't apply here though, because they used a 3 phase motor protector that must see full current on all three legs. To parallel the contactor contacts, you would need to separate the protector switch from the contactor. Hassle...


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## GEORGE D (Apr 2, 2009)

Fwiw


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## circuitman1 (Mar 14, 2013)

george , can you enlarge the wiring diagram & turn around?it looks kinda weird , that is the way the wires connect.


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## GEORGE D (Apr 2, 2009)

circuitman1 said:


> george , can you enlarge the wiring diagram & turn around?it looks kinda weird , that is the way the wires connect.


Sorry circuitman, I recently converted to an android phone and noticed every picture I post is sideways after posting. Also, I can't touch and enlarge others pictures, I can only view it tiny. Wtf?


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