Compressor Current and Potential Relays Explained

[@stevemccord8233]

The best explanation of these two relays. I’ve worked in the field for forty years and anyone who works in the hvacr industry needs to understand this concept. Watching this video is one of the best ways to learn current vs. potential starts. This guy did an outstanding job. Thank God for KZbin.

[@jollyscaria1922]

0l hvac potential realy curent rely line1 linted s.c coil einzing starting point conted enizing out startung point comprssl1 .lined give ssme line coil m..çr ..ruing point c line 2 comin ponited

[@robertgaitskell7212]

Your explanation was brilliant, I am a tradesman of 36 years I also us these compressor kits, i have used them for the last 15years, I believe in them so much for the last 10 years this is all I use, but I use 2in 1s I prefer to use the correct rated overload, that’s just my preference. I know I have stopped many unnecessary compressor replacements. 6mths ago I found a 2 in 1 that had failed it had been there for 12 years the compressor was 18yrs old the original relay and capacitor lasted 6years, I fitted another 2 in 1 and it is still going.Anyone who thinks these kits burn compressors out hasn’t given them a chance. Sure some fail but this is only because the compressor was damaged and was going to fail anyway. Well done with you’re video.

[@jamesurquhart5410]

The combination of the Schematic along with the bench explanation is an absolute key to understanding the operation. Most of us who have gotten into these trades do so for several reasons. One of them being the sit in class and learn through books without practical application is enough to bore us stiff. Again this combination is critical to understanding. Well done!

[@tmst2199]

If you think you're sitting in class learning boring stuff, you're not really learning anything.

[@stansmith439]

This is the best video I've ever seen on explaining the differences in these relays and how they work. Great Job! You are appreciated sir.

[@jerrymiller4754]

One of the best videos for start relays, etc on refrigerant compressor!

[@sonyxperiathree4554]

First good video on the explanation of how to repair a non starting compressor. If you know how something is designed you can figure out your own troubleshooting approach and why it failed . Most of the people creating these types of how to videos don't have a clue as to how these systems work. They only tell how to throw on a Support 3 in 1 as a repair solution. After seeing this video I see why the Supco could damage a compressor. BTW the start capacitor is there to prevent the premature burning of the relay contacts (like the condenser used in old distributor/points automotive ignition systems) while the run capacitor is for power factor correction. This why the smaller HP compressor units don't have a start capacitor while larger (higher current compressors) do employ them as contact burning is more acute. Thanks for the great explanation of compressor starting circuits.

[@vernroach3413]

As often as I have wanted to, I have never taken these relays apart since I knew what was going on in them, but this video is excellent at showing exactly how they work and I will use this technique since I soon, will be instructing again...I'd like to put one in every students hands for weeks, have them know them inside and out, like they make you take your rifles apart, again and again in the Army, until your know them personally...My thanks to the gent that made this video...Excellent work my friend.

[@cdrive5757]

SGT Gavens was satisfied only after we could strip and reassemble a Garand in the dark! ;-)

[@kaundabwalya7776]

Indeed this the best❤ video distinguishing between the two relays.. I agree with someone in the comment section.. Thanks 4 putting in the great effort Man🎉

[@francoisguyot9770]

Every clear and detailed explanation of an essential component of refrigeration systems that makes troubleshooting easier to perform. Thanks! Well done.

[@Gary-ts6dh]

9:06 - The click you hear might be the Choral "conductor" tapping his baton on the music stand indicating he wants the compressor to stop humming that (60Hz) pitch. 13:43 - a little dot of silver solder on each of those contact points, and you're back up and running.

[@mijodo2008]

Simply one of the best explanations of this subject on the net. Mate, your blood is worth bottling. Cheers From Michael. Australia

[@MohamedUAE]

When I looked at the line from C to R and from C to S, I started laughing! I guess people can tell from the line whether you're right or left handed :).. well done over all.. I loved the video man.

[@knewland5455]

great explanation, I'm not in the field however am trouble shooting my u-line fridge. i understood your presentation completely. (Very Much Appreciated

[@spelunkerd]

After years of searching, i finally found your video, explaining something I always wondered about. If you don't know how these little things work, you have no hope of understanding a schematic wiring diagram.

[@raindropsrising7662]

Thanks. Appreciate you putting everything together here. Watching for the 5th time and it's clear and AWESOME for a novice like me.

[@DOWNUNDER.]

Thanks ! did a potential start relay today, got the terminals mussed up, got it running. But it's nice to see I eventually got it right

[@andrewvickery1898]

Very informative and educational. I deal only with current relay systems at work and now have to fix the AC unit on my motorhome that is a potential system and was totally lost. Thank you so much for the video as I can now confidently diagnose the problem.

[@brownzimba4745]

wow the best teacher i hv never had

[@ebrahimsarrami1373]

Very expert and clever teacher.Thank you Sir.

[@yeomansbob]

Great video. Covered everything needed but in an understandable way. Good info delivery ability. Keep it real!

[@hbradar1]

On a PSC MOTORS the start winding is in circuit all the time. Induction motor they drop out.

[@NordicDan]

I like your explanation of the hard start kit. In a pinch I had to settle for a 2-wire since it was roasting outside and it was all I could get locally when my compressor began having trouble starting. I plan to change it out for a 5-2-1 as soon as I can to hopefully last until I change out the whole system.

[@kurtbjohnsoninc]

BEST EXPLANATION TO NOVICE - thank you

[@sayedhussain8503]

Great video, the gentlemen knows what's he talking out, he has a good experience .

[@waynepowell567]

Excellent break down . One of the best that I have seen. You do a great job of presenting this as well. Really appreciate your video. Thanks again. Great stuff.Covering a subject that most do not and seems an important part of the industry.

[@v63vav]

Thank you from Geosolar, Bulgaria!!! Very good explanation!

[@wdennis8]

Your video is fantastic. Your explanation is top notch. Thanks dude

[@gregrichard9192]

Great video Sir. Very informative. "The reason it's humming it's not because it do not know the words, but it's trying to start". 😀

[@Rs26-t3w]

I laughed out loud when he said this. Great job Halligan142!

[@CSSIandAssociate]

Very good explanation. In addition thanks for pointing out the contacts. Also, yes change everything. If you were doing it yourself you would. Done, piece of mind. No worries for a long time. In my home and on the vehicles. In the military we had something called. Preventative Maintenance Inspection Schedule. I think I retired in 2008 getting rusty on the acronyms. However if you schedule certain things they are taken care of. I do everything in the summer when it is easy. I now have a heated insulated garage which helps. Yet, summer time is best to tackle these items. Currently with the Hurricane I have just ordered the Transfer switch to the main breaker of the house so the generator can be hooked up just in case. After the fact kind of late.... Keep up the good vids. Very informative.

[@richardhowlin6048]

Excellent explanation 👌 sometimes someone can just explain something and it just clicks

[@poolmotorrepairguyFL]

The Florida pool pump motor bearing repair guy When Service Calls Longwood approved ! that was good info

[@chrisshea4269]

Great video for me, who was trying to get some more context on how all these parts work for a DIY fridge repair. Installed a 3n1, but ultimately the compressor seized again ultimately the thermal fuse did not stop power the circuit breaker did.

[@kenzpenz]

Great video. I will never replace or work on my compressor, but this sure was interesting. Yes I watched it all the way through and no fast forwarding. I always wondered what makes things work and this video was very informative. Thanks for sharing...Ken

[@scottk0623]

I use them also, I have had good luck with the 3 in1 lasting. I try to find the cause of the original failure,most times it’s either a unit on its last leg or the condenser is PLUGGED or fan bad. I have no problem leaving it on the unit. Most customers don’t want to pay for the 2nd call to put OEM parts on a white elephant anyway. Great video thanks.

[@jaimelopez7486]

Excellent explanation, clear, concise and precise, appreciated it very much.

[@diazcuba]

Hi, This is a great explanation of how a compressor winding is put together, my problem is that I have only two wires going to the connector and only on two of the pins of the compressor. I'm not getting any continuity on the one pin where there's no wire going to it. My questions are: Are all pins supposed to have continuity between each other, the one that has no wires has no continuity? If there is no wire going to the right pin on the connector of the compressor, does it still need to have continuity? I need to know if my compressor is bad.

[@samsen201]

Very educational. Thanks for explaining so well and clear. Well done job.

[@picwick57]

Installed an RCO410 last year worked great until recently after 2 days without power. would not start compressor for fridge to get up & running once power came back on. I ordered another one hopefully it solves the issue.

[@stanwei157]

I think you should explain how alternating current start capacitors' phase shift and motor's "BACK EMF" voltage created to drop (open) the starting circuit relay out as soon as the motor is running.

[@rickstadel5285]

I'm not so sure: If the viewer needs that explained, they're probably missing some needed background in electrical theory, without which 'phase shift' and 'back EMF' might only confuse them further.

[@ncooty]

@19:15: You misspoke, right? You meant the back EMF opens the potential relay and kicks out the start CAPACITOR, not the start WINDING, right? The start winding still has a current route via the run capacitor, such that the start winding is energized as long as the circuit is energized and the run capacitor works, right?

[@54egg]

Great video. Thanks. I was wondering if I could just measure voltage drop across hard start relay at start up, expecting maybe just a few volts until compressor gets running. One thing that did occur to me was to disconnect fan for compressor start up test so I can better hear compressor start or not. Of course not leaving fan off for more than short test.

[@Lvaman]

Excellent, thanks for the great clear explanation of how things work. My fridge works now! What was wrong? It has a PTC instead of the relay. It's a larger sized Danby. The PTC disc had a small piece broken off one side and a bit of corrosion and pitting. I sanded it all off, cleaned it up and wondered if it would still work. It did! So far so good. I'm still waiting for it to complete it's first cycle. Is there a polarity for the PTC? I noticed that one side is different but no markings.

[@robinfrancis789]

Good video....however....at around 6:53, you say the current relay opens and the start winding drops out.....but the capacitor ( which unless I missed it) you do not say if its a run cap or start cap, is providing a circuit by passing the relay whether its open or closed....or certainly the way its drawn.....I'm probably wrong....but your SC doesn't look like its in the wrong place....surely the SC must have to be in series with the relay switch....or how else will you remove if from the circuit after starting?.....can you please clarify? thanks 🙂

[@naeemmaqbool9311]

Very nice explanation of two relays used in a copressor

[@rj.parker]

Another option for single phase Copeland compressors is *Secure Start* by *Emerson* (actually a rebrand of an Australian company). It provides an electronic soft start capability to ensure zero crossing and low amperage startups. The Australian company is *Hyper Engineering* and the same single phase product is called *Sure* *Start* . They also sell a three phase soft start. Of course the new "inverter" based systems also are soft start inherently and are actually three phase vfd driven at the compressor even when sourced by single phase.

[@glasser2819]

Txs for this info. "soft-starters" are great to prevent destructive in-rush and preserve bearings on all electric motors greater than 1/2 Hp.

[@grahamswain7356]

A wonderful video ,can impressed see again .So interesting much appreciated many thanks .

[@stormfully]

Thank you! I've learned everything I needed to know :)

[@footprintsinconc]

2yrs ago, the 45/7.5 capacitor died, and now the fan side of the 45/7.5 capacitor died 1 week ago and i found the compressor humming (wasn't cooling house down). it must have been humming for 5hrs or so before i realized the house was not cooling down. i bought a new 45/7.5 dual run capacitor, and i also bought a 5-2-1 brand (csru2 model) and added it to my carrier 4Ton ac that is 6yrs old. i added it because from what i have read it helps start the compressor start faster and thus helps with its life....questions: 1) is it true that it helps with compressor life? should i have added this? 2) you said that once a capacitor goes out, we should replace the relay...which capacitor are you talking about, the 45/7.5 dual run capacitor or the 5-2-1 added capacitor? 3) how do i know looking at the unit what size my dual run capacitor should be...is there a sticker on the body of the unit that should say so (can't find that info on the my stickers)?

[@boogieman6661]

This was excellent. Thank you for sharing.

[@romeogad6680]

very well explained, that helped me a lot thank you

[@howardostfeld3802]

Excellent presentation for the "lay" person. May I suggest that you add a PTC relay in series to the start winding in your very first diagram? Otherwise, the relay through the run winding will always keep the start winding in the circuit. Also, may I suggest you change 120V to 240V? Most heat pumps and condensing units use 240VRMS single phase. Keep up the good work when you have time and if you need help with future presentations that get further into it, let me know. I have oscilloscopes and a lot of instrumentation equipment.

[@Do_the_Dishes]

Howard Ostfeld, You seem like the person to answer a question since you picked up on that fact. If I may ask. Concerning these “Hard Start Kits”. I know that the start capacitor and start windings are there to shift the phase in order to get rotation going. Are the kits simply there to increase the capacitance? If so, why doesn’t the manufacture simply use a higher rating capacitor? Can these start kits create too much starting torque or cause other problems elsewhere? Thank you in advance.

[@howardostfeld3802]

@@Do_the_Dishes Hello, I just saw your question. I want to give you an accurate and quantitative answer. It can get quite mathematical involving capacitive reactance and inductive reactance involving phase angles. These involve vectors. Let me know how far into it you want to go. The general answer to your question is that the combined inductance and capacitance has to be matched to the operating characteristics of the motor in the compressor to produce enough phase shift between the voltage and current for the motor to start turning. A simplistic analogy is, if you are not in the right gear for the engine speed for a manual transmission the car will not run smoothly. Thanks. Hope you reply.

[@rj.parker]

There are two scenarios described in the video. The FIRST is a fractional hp 115vac motor. In most cases these are called single phase induction motors, either cap start or cap run. The usual wiring has their cap in series with a switch or current relay. The SECOND scenario are larger several hp single phase compressors, typically 240vac 1-5 ton systems. These are PSC (Permanent Split Capacitor) Motors. On those, a capacitor is "Permanently" in series with the start winding. It is called a Run Cap and allows continuous start winding current. The amount of current is limited by the uf size of the Run cap. For a larger compressor, the Run Cap may be sized at 30-80 uf. A "hard start" kit for a typical single phase PSC motor adds another bigger cap in parallel to the Run cap "Temporarily" for more start winding current. The hard start cap, often around ~300uf, is switched out by a potential relay as soon as the motor comes up in speed. However in a PSC motor, the Permanent Split (Run) Capacitor stays in the circuit. Finally most PSC compressors in the last 25 years are scrolls which usually don't need extra hard start kits and use only their Run caps to allow current to their start windings.

[@mojetrouba]

Thanks for making this really helpful video. I’m a bit confused on the capacitor wiring. It seems to me, when the starting relay closes, it takes the start capacitor out of the circuit (it is shorted out) so how is that capacitor helping to start the motor? And, if true, once the relay drops out, it looks like the capacitor is in series with the start winding which I think is more like a run capacitor. But then it should be in the Run leg???

[@dantronics1682]

the cap is to stop arcing when the starter switch opens

[@Do_the_Dishes]

Dadla Ponizil , I was reading the comments to see if anyone else picked up on that. The start capacitor should be in series with the switch; only the run capacitor would parallel it so his print is wrong. In addition, the cap is not to stop arcing in this case. It is to shift the phase in order to start the rotation going.

[@rj.parker]

There are two scenarios described in the video. The FIRST is a fractional hp 115vac motor. In most cases these are called single phase induction motors, either cap start or cap run. The usual wiring has their cap in series with a switch or current relay. The SECOND scenario are larger several hp single phase compressors, typically 240vac 1-5 ton systems. These are PSC (Permanent Split Capacitor) Motors. On those, a capacitor is "Permanently" in series with the start winding. It is called a Run Cap and allows continuous start winding current. The amount of current is limited by the uf size of the Run cap. For a larger compressor, the Run Cap may be sized at 30-80 uf. A "hard start" kit for a typical single phase PSC motor adds another bigger cap in parallel to the Run cap "Temporarily" for more start winding current. The hard start cap, often around ~300uf, is switched out by a potential relay as soon as the motor comes up in speed. However in a PSC motor, the Permanent Split (Run) Capacitor stays in the circuit. Finally most PSC compressors in the last 25 years are scrolls which usually don't need extra hard start kits and use only their Run caps to allow current to their start windings.

[@charleseggers6176]

Thanks. Very informative 👍

[@jeremysolis3185]

Excellent excellent video 👍🏼 Thank you 🙏

[@jamesr.dubose6469]

Great explanation. Thanks so much of an excellent presentation.

[@nickush7512]

Superb Dude, many thanks.

[@axemanjoe2945]

Is it possible for the potential relay to test good but actually be bad as well as start and run capacitors?

[@edmundochaparro-barriguete1215]

Great explanation. A little observation; a pronunciation between Star or stock I was confused. Another issue; if my refrigerator does not have a visible capacitor, together with the relay, where is it located?

[@andrewcummings267]

REALLY ENJOY YOUR Experience and expression this video has been very interesting on those components hope to work with you one day

[@Sor91785]

Those start winding's look like they are getting amps regardless of that current relay being open or closed in your diagram. The only thing I can think is that it wont overheat because the electricity will take the path of least resistance through the run winding's. I'm in school right now and our teacher is having us connect a pictorial diagram together with a current relay and overload- the relay has N.C contacts, and so far it seems like to me like L1 should feed power to the current relay first and then onto the motor so it can actually isolate the start winding when that switch opens from the electromagnetism. Would love to hear your thoughts, friend.

[@xraybravo7180]

Awesome explanation and great speech skills

[@DA-lq9kp]

You mention a PTC (positive temperature relay). If the PCT stops the flow of current by temperature does it not cutback in when it cools down and then cycles the whole time the compressor is in use? I can now answer my question: The Standard PTC relay device has a PTC chip in series with the start winding. PTC or Positive Temperature Coefficient devices when cold, have a very low resistance, but when heated their resistance will go very high, a thousand times higher than when there cold. So when the compressor is ready to start, the PTC relay must be cold .so when power is sent to the compressor the power goes directly to the run winding and also to the start winding via the PTC device. Within a second or so of the compressor starting the power to the start winding is virtually cut out due to the PTC device rapidly being heated by the power drawn by the start winding. The power to the start winding is now virtually nothing ,simply a small current to keep the PTC device warm and the start winding out of circuit while the compressor is running. When the compressor cuts out the PTC cools down and it’s resistance drops to around 25ohms ready to restart. The PTC requires about 5 minutes to fully cool down so that it’s resistance is low enough to energise the start winding due to cooling demand.

[@rlg222]

Thanks for the explanation!

[@charlescardinal3093]

Still, Are they using the start winding as a run winding thrue a small capacitor as contrairy to a generic starter.4SP

[@thomasernst4894]

...great video...how can I test a PTC relay with a meter and tell if it is good...Thank you...

[@Halligan142]

Measure across the contacts at room temperature. If you have low resistance like 100ohm or less than the relay is most likely ok. If you have the tech specs of the compressor it will sometimes tell you resistance values at certain temps all are different. The parts are pretty cheap and there is a generic version for compressors without the start capacitor that are carried by most supply houses so of you suspect the relay change it out.

[@thomasernst4894]

...Thank you...

[@billysgeo]

So, do those potential (voltage) relays have a correct orientation ("up" direction) that they should be installed in?

[@MrWwoww123]

Potential relays do not require a correct orientation . The current relays do require correct orientation due to iron core inside the coil. Current relays are normally open. Then closes due to LRA (high amps pullsthe iron core to close the circuit). Then opens once the compressor gets up to speed.

[@MrWwoww123]

Well.. some might have a particular orientation. But i haven't seen one.

[@MrLaffertyheating]

Awesome video!! Look forward to the schematic series!! Thank u!

[@veganath]

*"It doesn''t hum because it forgot the words"* ....LMAO Thanks

[@chamindapeiris897]

Thanks from Sri Lanka

[@johnlorenz6795]

Great video. Great information. Thank you!

[@dennisjones1961able]

very informative video well done

[@Isobar20]

First, thank you for the detailed explanation. I have a question on PTC Relay on Supco 3-in-1 start kit. When high current flows through PTC it heats up and cuts the power going to start winding. This part is understood. What happens when the compressor starts running normally and the heat decreases inside the PTC will it connect the compressor’s start winding back again when there no need because the compressor is already running normally. Will my described process, PTC off-on continue until it will kill the compressor? Or I am missing something? Can you please comment?

[@yonasweldekidan2077]

The PTC will still be off (open) if the compressor is running,this is due to the current drawn by the compressor when it is running.But when (if) the compressor stops ,the PTC would cool down and it will be On.Again if you start the compressor again ,it will start and the PTC will go Off when the compressor is running.

[@sidadel5101]

Would be possible to show wiring with 30 amp contactor and 3 prong capacitors for 240 volts 2 phase?

[@davidjohnston3083]

I like Your explanation but I have a problem with the diagram. The start capacitor wont work if both sides of it are connected to the switch/relay contacts all it could do is discharge the capacitor. And with the switch open as pictured will energize the start winding through the capacitor all the time then over heat then cycle overload until something gives up the ghost.

[@DW-vl2wi]

I think you just saved me a ton of headache.

[@erdejo01]

How would you tell if your compressor may still be good?

[@juliand2709]

great explanation...

[@ferretface8782]

I need to see how everything is wired inside the 3n1 cap cover. The person who started this project unplugged everything from the 3n1 and I don't have a clue how it came wired as shipped.

[@johnson4940]

Why L1 (hot wire) first move goes to Common terminal but not Run terminal ? Anyone can explain?

[@Halligan142]

The relay switches the neutral. You want the hot wire to go to the overload which is attached to the common terminal so if the overload trips no power gets to the compressor.

[@johnson4940]

Thank you Sir it is absolutely clear, but could you please explain some times I see this current relay is put L1 (hot) to run terminal and, the neutral is to overload which is attached to Common terminal???

[@evelyn367]

nice one buddy it been said previously great vid great explanation

[@jeanfrancois7470]

Thankyou for good Explanation

[@mannyfilmsinc]

What a great video, and great explanation on how these things work. THANK YOU! Would you use a 3-1 in a small ice cream freezer? You mentioned earlier the thermostat, but is there room to wire it to the 3-1? thanks

[@samsen201]

No expert here but 3n1 s have long cables and can be left in a far place if adjacent to compressor you have lack of it. Then at under $10, you have nothing to loss to try one and see if it will run your unit, first and then will continue to work fine or not, in coming days. You can't make it worse and hope is that small price tag of 3n1, bring the cold back.

[@الاملالطائر]

Great work thanks 🙏 a lot

[@wraven8154]

Hi, I wanted to make this silent compressor so I got from my friend the ac compressor (from external unit) and I was wandering whether you would be able to help me with connection of the compressor ( ac was single phase) but there wasn't separate capacitor as I can see on some KZbin videos, there was whole like main board from computer and there were few capacitors, any way on the compressor itself is a label which says 148VDC, at 120Hz, and I have no idea how to connect it to a power supply, by the way I am in UK so as you know we have 220V.

[@Halligan142]

W Raven More than likely what you have is some sort of inverter driven compressor. A lot of mini split units use kind of a similar deal. That board was more than likely the control unit that ran everything. You’re probably not going to be able to get it running without knowing at the very least what unit it came from and getting a wiring schematic for that unit. There is a good chance you won’t be able to get it running.

[@seanmcdermott416]

Could you tell me then what purpose would a 521 hard start kit be used for ? Thanks

[@Halligan142]

It's a potential relay with a capacitor connected. 5-2-1 refers to the terminal connections on the relay. That's where it gets its name from. It's used to give compressors that only have a run cap (such as residential type splits) a boost to get started and reduce the starting time which in turn reduces the length of time of the load Spike and heat generated on compressor start up. It does not change starting amperage only the time the amperage is drawn. There is also a cheaper 2 wire version that gets wired in parallel with the existing run capacitor. I don't like those.

[@marklennon1580]

excellent training video!!!

[@naseemqureshi1966]

Can you please explain why relays are used to start compressor and what are the advantages & disadvantages of using start capacitor and run capacitors

[@FireandFrostHVAC]

Basically, relays are used to start a compressor because it is a single phase compressor motor and therefore only has two poles within the motor that are available to produce the torque required to get the motor spinning at startup, as opposed to six poles 120 degrees apart in a three phase motor. The relay (as is very well explained in this video) adds the start winding into the circuit to provide the extra starting torque required to get the motor running at startup, but because the start winding is a much higher resistance winding it will quickly overheat and burn up if it is left energized for any length of time beyond the initial startup (i.e. high starting torque) time period. Once the motor is running the current draw through the run winding will drop (or decrease if you prefer) from the higher inrush current value at startup, thereby decreasing the current flowing through the electromagnet, opening the contacts on the start winding and dropping the start winding out of the circuit. The only “advantage” to using a capacitor start capacitor run (CSCR) type of compressor motor is that it allows manufacturers to produce small fractional horsepower refrigeration units that can utilize single phase 115V or 230V power. The only purpose of adding capacitance (or inductance) into an electrical circuit is to phase the voltage and amperage peaks at different times during the cycle - in the case of capacitance the phasing is negative and the current will lead the voltage, whereas with inductance the phasing is positive and the current will lag the voltage. You should google phase relationships in single and three phase circuits if you want a more in depth explanation. The disadvantage to CSCR motors is the extra cost of the starting components, the eventual failure and required replacement costs for those components, and the fact that three phase motors will use less current than their single phase counterparts to produce the same horsepower or mechanical work. Hope that helps.

[@davidmcvicker8577]

One comment to make,shouldn"t you have meg ohmed the windings to see if you have damage on the windings

[@maar5725]

' شكراِ لّك ؛ Thanks ; It's very informative .

[@JoshKilen]

very nice info, does this work with normal air compressors?

[@charanjitjammu693]

Very nice sir.

[@paradoxdea]

I like the video, but there's a big difference between LRA and FLA. The compressor amps peak when it reaches full load amps. If the compressor motor sticks, or if the compressor itself is frozen, then locked rotor amps occurs.

[@nogeek43]

Good information and well done. Now I can talk more intelligently with my HVAC repair man.

[@pululo98]

Those replacement relays (3 in 1) work but won't last much, I replaced one of those and it only lasted a month, it is better to get the original relay.

[@crappie72]

nice video.................................lobstah

[@beaverman011]

Great Video. Thanks for sharing your knowledge, learned a lot. Just had one comment. All these burned contacts which can lead to major failures, I wonder why there's no component to help absorb that electrical arc. All the old automobiles with points and condenser ignition used the condenser to protect the points from burning. You would think they could incorporate a condenser of some sort into the system. Just a thought, I'm no engineer. Thanks again

[@n.mcneil4066]

Actually the automotive condenser is a capacitor. In the small fridge current relay the capacitor is in parallel to the contacts in the same way as the condenser (capacitor) is in parallel with the contact points of the ignition,

[@Jimmyzb36]

Thanks for the Theory!!!!!!!

[@pavankumar-zm8jm]

Good explanation man. I wonder that i watched a complete 27;16 min video... Where are you working man.. Ni

[@howardtoob]

Can anyone tell me a potential relay can be used to replace a centrifugal start switch in a 5hp air compressor motor? It is a single phase Baldor (old USA-not chinese) 240VAC motor and the switch is bad . A potential relay seems much cheaper and more reliable??? Thanks

[@glasser2819]

yeah I believe a potential relay (or better: its electronic equivalent built around a Triac) would be a great replacement for centrifugal start switch.

[@chevyed2100]

Nice video. I ended up here after coming home to my house smelling like burned wires. I think it was the fridge but I can't find anything exactly wrong with it except that it's testing about 23-24-25 ohms on the compressor between connections. However, when it's running it is only pulling 1.3 amps on the compressor wire. My math says it should be more like 5 amps. I'm using a Greenlee meter though, not calibrated. I recently tested it against one that was calibrated and it was good on the ohms and DC voltage. Do you have any thoughts? Is that compressor bad?