Phase Protecting HVAC/Refridgeration

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About a dozen times per year we lose a condenser due to phase loss (out of 150 condensers in the field).
A small percentage of the condensers have an upgrade on them for protection from phase loss.
But in 99% of the failures, the phase loss is due to the contactor contacts, rather than something up stream.
Therefor the typical phase protector would be monitoring phases in front of the failure and not see the failure.

Is there an easy turn-key solution for monitoring phase loss due to contactor failure? I know the condensors can withstand a phase loss for a limited amount of time. I could probably rig something up with a TDR combined with a phase monitor and take a guess at what amount of time to set it for. But it seems like the industry should already have something out there to solve this problem.

On a related subject...
Is there a solid state contactor out there, that is more reliable than the typical mechanical contactors I see in the field? Perhaps one that monitors the final output of its own triacs (or however they work) and shuts down if the triac fails.

On a related subject...
Is there a solid state defrost clock out there, that is more reliable than the typical mechanical defrost clocks I see in the field?
 
Why not just connect the phase loss monitor on the load side of the contactor?
Thank you for your reply.
My understanding is that every time the contactor is De-engergized (such as when thermostat is satisfied or defrost cycle is running), it would read it as a phase loss.
 

StarCat

Industrial Engineering Tech
Location
Moab, UT USA
Occupation
Imdustrial Engineering Technician - HVACR Electrical and Mechanical Systems
ICM Choices

ICM Choices

Why not just connect the phase loss monitor on the load side of the contactor?

You are wiring the protector in series with the compressor contactor coil. If you put it on the load side your contactor would not pull in because the device would not power up. The cart has to be behind the horse.

ICM makes a protector that does monitor line and load but they are quite a bit more expensive and they are large.
The Load wires are typically landed on the load side of the contactor, but in some cases you can take them all the way to the motor.
I have installed quite a few of them both on HVACR and other applications:

http://www.supplyhouse.com/ICM-Cont...-1-5-Minutes?gclid=CIvq8uDjxMYCFQeBaQodvkMOaw
 

templdl

Senior Member
Location
Wisconsin
About a dozen times per year we lose a condenser due to phase loss (out of 150 condensers in the field).
A small percentage of the condensers have an upgrade on them for protection from phase loss.
But in 99% of the failures, the phase loss is due to the contactor contacts, rather than something up stream.
Therefor the typical phase protector would be monitoring phases in front of the failure and not see the failure.

Is there an easy turn-key solution for monitoring phase loss due to contactor failure? I know the condensors can withstand a phase loss for a limited amount of time. I could probably rig something up with a TDR combined with a phase monitor and take a guess at what amount of time to set it for. But it seems like the industry should already have something out there to solve this problem.

On a related subject...
Is there a solid state contactor out there, that is more reliable than the typical mechanical contactors I see in the field? Perhaps one that monitors the final output of its own triacs (or however they work) and shuts down if the triac fails.

On a related subject...
Is there a solid state defrost clock out there, that is more reliable than the typical mechanical defrost clocks I see in the field?
Phase Monitoring Relays

I used the Westinghouse SVM, systems voltage monitor years ago. Today it appears ass though the EatonD65 offers similar features:
Eaton’s D65 Series Phase Monitoring Relays prevent motors from running at temperatures above approved ratings, and provide protection against phase loss, phase reversal, and phase unbalance due to blown fuses, broken wires or worn contacts. They monitor simultaneous voltage drops/increases, and help to prevent damaged machinery and the injury of personnel.
Prevents reversal of phases when modifications are made to the circuit for worry free maintenance.
Prevents motors from running at temperatures above approved ratings for added safety.
Prevents three-phase motors from continuing to run after losing a phase that could result in motor burnout.
 
Looks like you guys pointed me to the solution...thanks !
The only kind I have seen in any equipment in the field are the ones that only monitor the incoming voltage. I did search HVAC talk and found them referring to the same basic type. BTW...even the basic ones I have seen in the field will protect against phase reversal.
Now I need to figure out which ones would be the most reliable. I don't want to solve one problem and create a new one. A similar reason why I am looking for a solid state defrost timer to replace the mechanical type that fail every few years.
Thank you all for the responses.
Thank you moderators for deleting the brand sales pitch that I almost fell for.
 

kwired

Electron manager
Location
NE Nebraska
The motor should be able to handle the condition long enough for properly selected overload protection to respond - JMO.

But also does little good if overload automatically resets - which could be common in this type of equipment as it just keeps cycling and eventually allows for too much heat in motor windings.

You could use overloads that monitor current imbalance for single phase protection, then it doesn't really matter where it is in the circuit, at least when used for protecting a single motor - multiple motor protection could be more complicated to ensure each motor is sufficiently protected - and I say this for the purpose of single phase protection only, actual motor overload protection generally needs to be individual protection for each individual motor.
 

templdl

Senior Member
Location
Wisconsin
Looks like you guys pointed me to the solution...thanks !
The only kind I have seen in any equipment in the field are the ones that only monitor the incoming voltage. I did search HVAC talk and found them referring to the same basic type. BTW...even the basic ones I have seen in the field will protect against phase reversal.
Now I need to figure out which ones would be the most reliable. I don't want to solve one problem and create a new one. A similar reason why I am looking for a solid state defrost timer to replace the mechanical type that fail every few years.
Thank you all for the responses.
Thank you moderators for deleting the brand sales pitch that I almost fell for.

This also brings to mind the time when (3)200hp 480v pump motors ar a WWTP were fried because the plant was single phased. An excavator dug up a feed because the POCO had not informed diiggers hotline of the recently installed underground feeder. I supplied the MCC starters with the Westinghouse SVMs that should have prevented the damage. I was called to a big meeting with the city comptroller, contractor, POCO, and my distributor. Before the meeting I asked to do a site visit at which time I discovered that the SVMs were left in the as factory supplied settings which allows them to be automatically reset back into the single phase condition leading to the motor failures.
At the meeting I pointed out that I can supply a means to prevent motors from being damaged with the instructions on how for them to be set but I can not do the settings for thern which was the contractor or engineers responsibility. The SVMs were specified and nobody bothered to set them.
$16k worth of damage was split between the city engineers, contractor, and POCO.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I was high bidder at our local village to supply monitoring of the well power supply. A few months later when a phase literally dropped and the well motor fried I was called in to tell them what happened. The low bidders were there replacing the motor and bitching about how the monitor did not work as it should. it got pretty quiet when I explained how it had never been hooked up correctly.
 

templdl

Senior Member
Location
Wisconsin
I was high bidder at our local village to supply monitoring of the well power supply. A few months later when a phase literally dropped and the well motor fried I was called in to tell them what happened. The low bidders were there replacing the motor and bitching about how the monitor did not work as it should. it got pretty quiet when I explained how it had never been hooked up correctly.
Thanks for sharing you experience.
In my case if another sales engineer would have attended my meeting they would have not had a clue and would have rolled over and given the municipality at least $4,000 of my company's money. I have seen 10s of thousands of dollars of my employers money given away by incompetent sales people.
 

mnbiker

Senior Member
Location
st.paul mn
I just ordered a new motor starter contactor for a chiller unit we have here. Its is a Siemens ESP200 electronic overload relay.

it has current transformers on each leg of the load to monitor current. it will trip out on overload, loss of phase, current imbalance, and ground fault.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Very simple. Replace your cheap little junk OL relays with solid state OL relays that monitor CURRENT, not voltage. They can't be fooled by regen on a lost leg like voltage sensing relays and if a single contactor messes up, the SSOL only trips THAT contactor, not the entire system. They are not much more than a bimetal OLs now and CERTAINLY less than adding a phase monitor to each contactor.

And if your contactors are failing that often, use better electromechanical contactors, not solid state. SS contactors put out heat, about 4-1/2 W/RLA through them and so they need to be kept cool and anything else sensitive to heat in the same box does too, which is difficult to do in most electrical panels. Then if you ventilate the box to get rid of heat, you pull in dust and dirt, which causes other problems. They are also sensitive to voltage disturbances, so they short just as much or even more than contactors in the wrong applications, such as wherever Wye-Delta starters are used, which happens a lot in 3phase HVAC systems (on the compressors).

The problem with contactors in HVAC is that the OEMs use the absolute cheapest crap available, called "Definite Purpose", often abbreviated "DP", that are DESIGNED to last out the equipment warranty, not a day longer. I always tell people that DP should stand for "Don't Purchase", because they are the worst of the worst as far as quality and longevity is concerned. Their mechanical components are also self destructive, so the HVAC equipment supplier gets to sell a replacement part on the first service call after the warranty is up.

If you have room, replace them with NEMA contactors, they will likely NEVER again fail in your lifetime on an HVAC load. If you don't have room, use an IEC contactor but over size it as much as possible for the available physical space. IEC contactors are built better mechanically, but are sized similar to DP as far as current capacity. So the higher rating you can squeeze in there, the longer it will last.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I just ordered a new motor starter contactor for a chiller unit we have here. Its is a Siemens ESP200 electronic overload relay.

it has current transformers on each leg of the load to monitor current. it will trip out on overload, loss of phase, current imbalance, and ground fault.

It is to bad that those units don't come with decent starters but much like irrigation Pump installers they don't mind selling new motors or in your case, compressors.
 

mnbiker

Senior Member
Location
st.paul mn
It is to bad that those units don't come with decent starters but much like irrigation Pump installers they don't mind selling new motors or in your case, compressors.

ptonsparky

could you fill me in on this, I have not used one of these electronic relays before. We have 3 chillers in an out building that is not air conditioned. On some very warm days thermals can trip out on the old starter.

thanks
 

templdl

Senior Member
Location
Wisconsin
ptonsparky

could you fill me in on this, I have not used one of these electronic relays before. We have 3 chillers in an out building that is not air conditioned. On some very warm days thermals can trip out on the old starter.

thanks

One could also consider if the thermal OLRs are located in the same aambient temperature as the motors that the motors would be running hotter also because the surrounding air is warmer. Consider that even though the actual runnings may not change the motor would be running hotter because of the ambient air termp. As such it may be advantagious for the OLR to create as the ambient temperature increases protecting the motor. If so it shouldn't be considered as nuisance tripping.
 

templdl

Senior Member
Location
Wisconsin
It is to bad that those units don't come with decent starters but much like irrigation Pump installers they don't mind selling new motors or in your case, compressors.

Decent starters are relative. Today it is common to use IEC rated starters which are very sensitive to the application which often time does not provide anything extra. NEMA rated starters are must more robust and are generally larger and more expensive than its IEC counterpart.
Widely used IEC utilization categories include
AC-1 for purely resistive or only slightly inductive loads, such as heater circuits
AC-3 for routine starting and stopping of a squirrel cage motor and only occasional jogging
AC-4 is similar to AC-3 but includes inching and plugging (jogging and reversing at speed), requiring significant instantaneous control of the motor current
 

kwired

Electron manager
Location
NE Nebraska
ptonsparky

could you fill me in on this, I have not used one of these electronic relays before. We have 3 chillers in an out building that is not air conditioned. On some very warm days thermals can trip out on the old starter.

thanks
Are you asking for more information on the ESP overload units?

If so have you looked at this page or similar documentation?
 

StarCat

Industrial Engineering Tech
Location
Moab, UT USA
Occupation
Imdustrial Engineering Technician - HVACR Electrical and Mechanical Systems
Defrost Timers

Defrost Timers

Looks like you guys pointed me to the solution...thanks !
The only kind I have seen in any equipment in the field are the ones that only monitor the incoming voltage. I did search HVAC talk and found them referring to the same basic type. BTW...even the basic ones I have seen in the field will protect against phase reversal.
Now I need to figure out which ones would be the most reliable. I don't want to solve one problem and create a new one. A similar reason why I am looking for a solid state defrost timer to replace the mechanical type that fail every few years.
Thank you all for the responses.
Thank you moderators for deleting the brand sales pitch that I almost fell for.

I've never seen any defrost timer on the market that is more reliable than the old school Paragon mechanical style.
If you have another candidate, I'd like to check it out.
They do fail yes, but the others I have come across are horrible.
The paragon timer needs the right kind of lube on the gear portion now and then to extend service life.

About the advent of Solid State as it came heavily into HVACR.
A very small percentage of modern solid state control systems are Well Engineered and work like they should.
A very large percentage of them are Very poorly Engineered, and even more badly contructed.
Many modern HVACR control boards are riddled with all manner of operational problems that take them down often and waste countless labor hours dealing with problems that rise out of instability, intolerance of dirty power, and just plain bad control logic designed by persons that are out of touch with the
" field."
I have a friend back in Texas who is dealing with some of the most ridiculous machinery from York that possibly ever was.
How their Engineers are able to escape the consequences is beyond me but I have seen other major examples on even larger more expensive systems.
The Bigger industrial level gear such as the Trane Centravac etc. will show better control design because that level of investment cannot tolerate sorry controls, but on smaller tonnage gear bad circuit boards are rampant and getting worse.

The Best HVACR Control systems are hybrid style having very lean, well working and well designed circuit boards in conjunction with some smart relay logic utilizing relays that can be REPLACED.

All the best
 
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