Soft Starters for Air Conditioners

snoobler

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Are you aware the DC-DC converter is limited to 70A output?

Are you aware that the usable storage of the HV battery is almost exactly the same as the stock AGM 12V? This assume that the battery is brand new. Most packs are substantially below rated.
 

RCinFLA

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Attached may help.

Easystart goes through five training startup cycles. Final ramp selection is set on sixth startup.

My 4 ton A/C original factory stock start surge was 200 amps for 400 msecs. My A/C has Copeland Scroll compressor which are nasty for startup surge. After training the final start surge dropped to 74 amps. The fifth training cycle actually went down to 64 amps but could hear it was getting close to stalling out. It auto selected the fourth training result which was 74 amps. That was well within max surge capability of my inverter.

These softstarters have two mechanisms to reduce startup surge. There is the traditional triac voltage ramp up but they also have the temporary insertion of larger start capacitor to boost full 360 degree rotational torque.

Locked rotor spec is for sizing maximum branch circuit breaker amperage. It is spec'd at minimum AC line voltage allowed, so actual nominal AC voltage startup surge is usually higher then LRA. Wire gauge and run length has impact on startup surge.
 

Attachments

  • Cap Start Induciton Motor.pdf
    224 KB · Views: 16
  • Trane Easy Start hookup.pdf
    362.1 KB · Views: 14

svetz

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Thanks for posting your application, cool to see others doing this!

Trying to figure out how to wire it in. I look at the diagram, and they seem to only show the 'run' cap in their circuit. Does this mean we omit the 'start' cap completely?
Mine (different company through) had a replacement cap inside the unit, I suspect that's how they're getting the startup amp reduction. So, I think you're right, but I'd still wait to hear back from them.

And Hyper Engineering doesn't really show how the centrifugal start/run switch ties into the circuit. Is that omitted along with the start cap?
AFAIK, that switch just cuts power to the start cap, it should be wired (somehow) into the HE so it "knows" the motor has started.

The manual says, 'make sure you uninstall any previously installed hard-start kits'... Wondering if that means the factory centrifugal switch and start cap circuit?
No, a "hard-start" kit is a kit like a soft-starter... they're a lot cheaper but don't do as good a job. Some manufacturers have them pre-installed. Didn't see it in your wiring diagram, but make sure there are no caps on the device unaccounted for in the diagram.

I did send a message with my questions to Hyper Engineering
Let us know what they say, curious now.
Trying to make sense of it, hopefully I don't damage the gaskets that hold the smoke in...

.... or people could just cheer me on and cross your fingers for me and we'll see what happens....
🤞
 

GSXR1000

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i use the micro air (board version) on my RV and i can start my 13500 btu ac off of my honda EU2000I on eco mode no problem. Even once plugged my RV into my 1000w inverter and it ran off of it (beeping on and off the entire time) Per my fluke clamp meter my max amps never go over 11 amps and running is 7-10 amps

This one is for 4 and 5 ton
 

RCinFLA

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A 'Hard start' kit is just an added starter capacitor. It is engaged during startup to increase starter winding current. They typically have just a timed out relay opening or have a positive temperature coefficient thermistor to disengage added starter capacitor after about 0.5 sec startup period.

They are intended for situations of low AC line voltage or high initial mechanical load on motor. They do not have a triac voltage ramp circuit. They usually increase the motor's startup surge current but for a shorter time period and can be damaging to start winding of motor if added start capacitor is too high in value.

Usually 'Hard Start' kits are not too helpful in relieving startup surge on an AC inverter. Only benefit in this situation is they may shorten the length of time of high current startup surge to something the inverter can handle although this is not usually sufficient.

A softstarter alone on a single phase induction motor reduces surge current but lengthens startup time. The reduction is usually not enough when coupled with the extended startup time. You need both the softstart ramp and the 'Hard Start' starter capacitor boost, coordinated in time, to get the peak surge and time length reduced. This is what the MicroAir Easystart, SecureStart, and other units do.
 
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svetz

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You probably saw from the other thread, but my softstarter took the AC from a startup of 86.4 amps to a min of 22 amps (usually around 26-28, as high as 31). I have a really cool graph, but didn't get permission from MicroAir to publish it (they sent me a "special" unit so they could get remote diagnostics and do remote upgrades, it was the first time they were dealing with frequency shifting and wanted to ensure their product would work not only with Enphase's IQ8/Ensemble technology, but the utilities frequency shifting to throttle back solar production).
 
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ghostwriter66

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i use the micro air (board version) on my RV and i can start my 13500 btu ac off of my honda EU2000I on eco mode no problem. Even once plugged my RV into my 1000w inverter and it ran off of it (beeping on and off the entire time) Per my fluke clamp meter my max amps never go over 11 amps and running is 7-10 amps

This one is for 4 and 5 ton

from a EE perspective it seems very nice design ... but wish it was slighter less expensive ... (slightly as in A WHOLE BUNCH)
 

Samsonite801

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Well I received a response back from Hyper Engineering and their support team amended my wiring diagram I sent them, as they said these untis are typically used for A/C compressors (what the default diagrams in the instructions come with), and it even says in the manual, for other motor applications, please contact Hyper Engineering support team to assist in making correct wiring diagram for your application.

So here is the diagram (with markup):
1606801091337.png
1606801690094.png
1606801347796.png

To make a long story short.... It tried to start anyways!

Instead of just tripping the UPS inverter overload right off the bat like before, it starts to turn, ramping up, gets about halfway to speed and then trips my UPS overload. That inverter is a 3500w (5250w surge)...

It sounds to me like it will start if it has just a little bit more. I have another inverter which is rated 4200w (I couldn't find a surge spec but my guess would be 6000w or so?). I'm gonna try that one in a few days.

Hoping that one will start it... It does sound close, it definitely hits it a lot smoother when I turn on the power switch, it pauses for a second, makes a mild hum from the motor, and then starts turning slowly, and speeding up, then as it's getting on the throttle, it trips the inverter, whew hehe...
 

RCinFLA

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Well I received a response back from Hyper Engineering and their support team amended my wiring diagram I sent them, as they said these untis are typically used for A/C compressors (what the default diagrams in the instructions come with), and it even says in the manual, for other motor applications, please contact Hyper Engineering support team to assist in making correct wiring diagram for your application.

So here is the diagram (with markup):
View attachment 28992
View attachment 28994
View attachment 28993

To make a long story short.... It tried to start anyways!

Instead of just tripping the UPS inverter overload right off the bat like before, it starts to turn, ramping up, gets about halfway to speed and then trips my UPS overload. That inverter is a 3500w (5250w surge)...

It sounds to me like it will start if it has just a little bit more. I have another inverter which is rated 4200w (I couldn't find a surge spec but my guess would be 6000w or so?). I'm gonna try that one in a few days.

Hoping that one will start it... It does sound close, it definitely hits it a lot smoother when I turn on the power switch, it pauses for a second, makes a mild hum from the motor, and then starts turning slowly, and speeding up, then as it's getting on the throttle, it trips the inverter, whew hehe...
You are failing due to length of startup time or run current is just too much for inverter. Startup should not last more then about a half a second so any longer time would indicate insufficient inverter power handling capability for run current.

From the motor spec plate, the run power is about 3500 VA so using a 3500 watt inverter is not going to be large enough.

I looked up the Surestart install guide and did not see anything about training sequencing. This seemed a little strange. I doubt the best profile can be achieved from the first startup on a given motor size and particular mechanical load on the given application. You might ask their tech about this. Maybe it does training, just does it without telling you. If it does adjust without telling you it might need more attempts if it fails to startup on the first few tries. Obviously if inverter is just not sufficient it would have to give up after some number of tries.

Easystart tells you it prefers you train on AC grid mains so it is assured to have enough initial power to complete a startup. It then optimizes on subsequent startups.
 

Samsonite801

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You are failing due to length of startup time or run current is just too much for inverter. Startup should not last more then about a half a second so any longer time would indicate insufficient inverter power handling capability for run current.

From the motor spec plate, the run power is about 3500 VA so using a 3500 watt inverter is not going to be large enough.

I looked up the Surestart install guide and did not see anything about training sequencing. This seemed a little strange. I doubt the best profile can be achieved from the first startup on a given motor size and particular mechanical load on the given application. You might ask their tech about this. Maybe it does training, just does it without telling you. If it does adjust without telling you it might need more attempts if it fails to startup on the first few tries. Obviously if inverter is just not sufficient it would have to give up after some number of tries.

Easystart tells you it prefers you train on AC grid mains so it is assured to have enough initial power to complete a startup. It then optimizes on subsequent startups.

Yeah I do remember reading somewhere in the literature that it will take several starts for it to optimize. Unfortunately, I don't have any AC mains to test with as it's out at the storage unit. I don't even have a generator to test it with. The other thing I'm wondering about, my UPS inverter does have a voltage setting in it (set to 240v right now). It can be set to 200v, 208v, 220v, 230v, or 240v... My compressor motor is rated at 230v... I am wondering if a particular voltage setting would be better than another as far as the inverter goes. That settings has to be changed using SSH/Telnet to the inverter and I didn't have my laptop with me last night so I was not able to play with trying out 230v...
 

svetz

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Just in case someone is looking at Micro-Air, their cyber-Monday deal (today though 12/3/21) is 15% off the 364 (code CMEASY15) and 18% off the 368 (code CMEASY368). Info on mine is around #99.
 

GSXR1000

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Yeah I do remember reading somewhere in the literature that it will take several starts for it to optimize. Unfortunately, I don't have any AC mains to test with as it's out at the storage unit. I don't even have a generator to test it with. The other thing I'm wondering about, my UPS inverter does have a voltage setting in it (set to 240v right now). It can be set to 200v, 208v, 220v, 230v, or 240v... My compressor motor is rated at 230v... I am wondering if a particular voltage setting would be better than another as far as the inverter goes. That settings has to be changed using SSH/Telnet to the inverter and I didn't have my laptop with me last night so I was not able to play with trying out 230v...
inductive loads (motors, relays....) as voltage goes up amps go down, so 208 would be the most amps... but all voltages would be same watts... I would go with 240v so went voltage sags it is still high enough
 

RCinFLA

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Just noticed in picture, why is there a foil cap in picture? Pumps/compressors normally do not have foil run capacitors.

Normally there is an electrolytic high capacitance value starter cap on a compressor/pump. Is this something MicroAir told you to do. I can see with original high value starter cap with centrifugal switch on motor they may tell you to not add too much extra start capacitor value. The electrolytic start capacitor in Easystart should at least be the same capacitance value as the original stock starter cap that was controlled with centrifugal switch at end of motor.

The EasyStart would eliminate the need and wiring to centrifugal switch as Easystart unit controls how long the start capacitor is engaged. All you are getting from the EasyStart is the addition of softstart voltage ramp. You don't have the option of too much more starter capacitor boost without risking motor starter winding damage. A permanently connected smaller value foil cap to start winding will improve motor run power factor but not do much for startup surge improvement.

Usually a voltage softstart ramp alone lowers startups surge current but extends the startup time beyond the normal 0.4-0.5 seconds. The amount of surge current reduction is not great enough with the extended startup time. It may make the maximum momentary inverter surge capability but the extended time causes inverter surge time limit to be exceeded.

The reason pumps and compressors use a centrifugal switch with large value start capacitor is to increase their rotational torque during startup. Pumps and compressors have a heavy initial mechanical load from the get go.
 
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svetz

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Is this something MicroAir told you to do.
Which post/picture? A few of us have posted things and some of it is even hyper Engineering...
But, for my part it was just something attached without changing any capacitors. So far over a year and still ticking!
 

GSXR1000

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Just noticed in picture, why is there a foil cap in picture? Pumps/compressors normally do not have foil run capacitors.

Normally there is an electrolytic high capacitance value starter cap on a compressor/pump. Is this something MicroAir told you to do. I can see with original high value starter cap with centrifugal switch on motor they may tell you to not add too much extra start capacitor value. The electrolytic start capacitor in Easystart should at least be the same capacitance value as the original stock starter cap that was controlled with centrifugal switch at end of motor.

The EasyStart would eliminate the need and wiring to centrifugal switch as Easystart unit controls how long the start capacitor is engaged. All you are getting from the EasyStart is the addition of softstart voltage ramp. You don't have the option of too much more starter capacitor boost without risking motor starter winding damage. A permanently connected smaller value foil cap to start winding will improve motor run power factor but not do much for startup surge improvement.

Usually a voltage softstart ramp alone lowers startups surge current but extends the startup time beyond the normal 0.4-0.5 seconds. The amount of surge current reduction is not great enough with the extended startup time. It may make the maximum momentary inverter surge capability but the extended time causes inverter surge time limit to be exceeded.

The reason pumps and compressors use a centrifugal switch with large value start capacitor is to increase their rotational torque during startup. Pumps and compressors have a heavy initial mechanical load from the get go.
when you say foil do you mean metal? All run capacitor are metal. All single phase AC compressors use a metal run capacitors.

start capacitor are normally plastic yes.
ac compressor don't have centrifugal switches..
 

RCinFLA

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when you say foil do you mean metal? All run capacitor are metal. All single phase AC compressors use a metal run capacitors.

start capacitor are normally plastic yes.
ac compressor don't have centrifugal switches..
I was referring to Samsonite801 reply of shop air compressor picture above, not an air conditioner. Normally there is not a run cap in air pump compressor or water pumps, as their ON duty cycle is smalll. A run cap would improve run time power factor but the main issue with water pumps and air compressors is they have significant mechanical load during startup. They use large mfd. value elecrolytic starter cap with centrifugal switch to control starter cap engagement during the first 0.4-0.5 seconds of spin up.

For this particular unit, the air pump schematic shows both starter cap and run cap. The addition of run cap is likely for EU power factor regulations, not usually used in U.S. air pump, water pumps.

Problem with water pump and air pump is they already have the large mfd. electrolytic starter cap so MIcroAir, SureStart, etc units, are only effectively giving a softstart voltage ramp without the additional cap starter value boost. Just doing voltage ramp decrease startup surge current somewhat but voltage ramp alone also extends the startup time period.

The softstart voltage ramp surge current reduction may drop below a level short time tolerable by inverter but the increased startup time exceeds the length of surge time the inverter can support the reduced, but still significant surge current. Bottomline it does not allow the inverter to start the pump.

What the auxilary (start winding) does is provide effectively a two phase motor to create a rotating field to self start a motor. There are two criteria for accomplishing this. First is providing more current to starting winding and second criteria is the capacitor and aux winding inductance providing a 90 degree current shift to provide the best phasing for the rotating magnetic field and therefore increases full 360 deg rotational torque. The additional start cap value does not often optimize phase shift, only increases start winding current.

The aux/starter winding is typically physically place at 90 degrees to main winding. Since it is only intended to be used momentarily (<0.5 secs) the aux winding is typically wound with smaller gauge wire so have to be careful of pushing too much start winding current that may damage aux/start winding wire. The starter cap effectively provides a second 90 phase offset power source without the complication and expense of an inverter power supply like used in three phase variable speed motors.

This particular air pump has an extended auxilary/start winding with addition of run cap. The schematic SureStart recommended moved the start cap located in the Surestart box from the original lesser turns auxilary starter winding to the extended auxilary winding. This likely reduced the effect of the starter capacitor to increasing rotational torque.

On this air pump, need to know the size of the original stock start cap value, not shown on schematic, and what the substitued start cap within the SureStart unit is. With the voltage ramp, the starter cap value can be larger value than original stock value, something like 150%-200% of original stock start cap value without putting start winding at risk of damage.

For this air pump, I would recommend eliminating the run cap and not use the extended aux/start winding. Make the replacement start cap value in SureStart unit about 150% of the original air pump stock starter capacitor, and connect the SureStart start cap to the orignal starter winding tap position. If this large value cap is too big to fit in SureStart box than place it outside SureStart box.

Whenever changes are made, or Cap boost/softstart units are moved to a different motor, they usually have to be reset to original untrained state so they can re-learn the optimum ramp. Check softstarter manual or call manf. of unit to find out how to reset unit to untrained, factory default state.

Cap Start Induction Motor_2.png
 
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Samsonite801

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I was referring to Samsonite801 reply of shop air compressor picture above, not an air conditioner. Normally there is not a run cap in air pump compressor or water pumps, as their ON duty cycle is smalll. A run cap would improve run time power factor but the main issue with water pumps and air compressors is they have significant mechanical load during startup. They use large mfd. value elecrolytic starter cap with centrifugal switch to control starter cap engagement during the first 0.4-0.5 seconds of spin up.

For this particular unit, the air pump schematic shows both starter cap and run cap. The addition of run cap is likely for EU power factor regulations, not usually used in U.S. air pump, water pumps.

Problem with water pump and air pump is they already have the large mfd. electrolytic starter cap so MIcroAir, SureStart, etc units, are only effectively giving a softstart voltage ramp without the additional cap starter value boost. Just doing voltage ramp decrease startup surge current somewhat but voltage ramp alone also extends the startup time period.

The softstart voltage ramp surge current reduction may drop below a level short time tolerable by inverter but the increased startup time exceeds the length of surge time the inverter can support the reduced, but still significant surge current. Bottleline it does not allow the inverter to start the pump.

What the auxilary (start winding) does is provide effectively a two phase motor to create a rotating field to self start a motor. There are two criteria for accomplishing this. First is providing more current to starting winding and second criteria is the capacitor and aux winding inductance providing a 90 degree current shift to provide the best phasing for the rotating magnetic field and therefore increases full 360 deg rotational torque. The additional start cap value does not often optimize phase shift, only increases start winding current.

The aux/starter winding is typically physically place at 90 degrees to main winding. Since it is only intended to be used momentarily (<0.5 secs) the aux winding is typically wound with smaller gauge wire so have to be careful of pushing too much start winding current that may damage aux/start winding wire. The starter cap effectively provides a second 90 phase offset power source without the complication and expense of an inverter power supply like used in three phase variable speed motors.

This particular air pump has an extended auxilary/start winding with addition of run cap. The schematic SureStart recommended moved the start cap located in the Surestart box from the original lesser turns auxilary starter winding to the extended auxilary winding. This likely reduced the effect of the starter capacitor to increasing rotational torque.

On this air pump, need to know the size of the original stock start cap value, not shown on schematic, and what the substitued start cap within the SureStart unit is. With the voltage ramp, the starter cap value can be larger value than original stock value, something like 150%-200% of original stock start cap value without putting start winding at risk of damage.

For this air pump, I would recommend eliminating the run cap and not use the extended aux/start winding. Make the replacement start cap value in SureStart unit about 150% of the original air pump stock starter capacitor, and connect the SureStart start cap to the orignal starter winding tap position. If this large value cap is too big to fit in SureStart box than place it outside SureStart box.

Whenever changes are made, or Cap boost/softstart units are moved to a different motor, they usually have to be reset to original untrained state so they can re-learn the optimum ramp. Check softstarter manual or call manf. of unit to find out how to reset unit to untrained, factory default state.

View attachment 73053

Yeah, that aluminum cap was the factory run cap they indicated for me to keep in their marked up version of the diagram. I'm still trying to read your post here and wrap my head around all the details, it sounds like you have a pretty good idea on how I could better optimize my chances of getting it to start. I will see if I can figure out all of what you're saying here. Thanks.

1637526910009.jpeg

1637527219969.jpeg
 
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Njord

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Attached may help.

Easystart goes through five training startup cycles. Final ramp selection is set on sixth startup.

My 4 ton A/C original factory stock start surge was 200 amps for 400 msecs. My A/C has Copeland Scroll compressor which are nasty for startup surge. After training the final start surge dropped to 74 amps. The fifth training cycle actually went down to 64 amps but could hear it was getting close to stalling out. It auto selected the fourth training result which was 74 amps. That was well within max surge capability of my inverter.

These softstarters have two mechanisms to reduce startup surge. There is the traditional triac voltage ramp up but they also have the temporary insertion of larger start capacitor to boost full 360 degree rotational torque.

Locked rotor spec is for sizing maximum branch circuit breaker amperage. It is spec'd at minimum AC line voltage allowed, so actual nominal AC voltage startup surge is usually higher then LRA. Wire gauge and run length has impact on startup surge.

In the two drawing/files you attached there looks to be a contradiction that I'm hoping you might be able to answer.

In Cap Start Induciton Motor.pdf;
It shows the starting and run capacitor after the Triac, which would mean the Aux winding (Run and Start Cap) would also get a ramped voltage.

In Trane Easy Start hookup.pdf;
It shows the run capacitor before the traic (full voltage) and the starting capacitor after the triac (ramped voltage).

Should the circuit be like this?
1641762912636.png

This would also softstart the fan, whether thats desirable or not.
Or is the start capacitor shown in the wrong location and is actually before the Triac (Full voltage and in parallel with the run cap)?

thanks!
 

RCinFLA

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Your modification would triac voltage ramp both the compressor and fan. It may result in startup problems with fan motor as there will be no larger start cap during voltage ramp..

MicroAir also has a four or five second delay after main contactor closes from thermostat control before compressor ramp up starts. Having fan kick on immediately helps to get an inverter-generator out of ECO mode or AC inverter out of sleep mode before heavy compressor load begins.
 

Njord

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Your modification would triac voltage ramp both the compressor and fan. It may result in startup problems with fan motor as there will be no larger start cap during voltage ramp..

MicroAir also has a four or five second delay after main contactor closes from thermostat control before compressor ramp up starts. Having fan kick on immediately helps to get an inverter-generator out of ECO mode or AC inverter out of sleep mode before heavy compressor load begins.

That make sense. So then the block diagram showing the start capacitor is incorrect. Should be as per the below, before the Triac.
1641771625351.png
It seems like you have a pretty good idea hows these work and I'm trying to build my own with an Arduino. Thats the reason I'm asking specifically how its connected.


That point about the controller waiting 4/5 seconds before starting the compressor is interesting. that delay would start the fan (as you mentioned) and also apply voltage to the start winding and capacitor.
If you have any more information on how the voltage is ramped (say 30%-100%, or maybe they step it, 50% then 100%), or any other aspects; I would like to know more.
 
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