Soft Start for Motors

DanS26

Re: Soft Start for Motors

Installed the soft start today. Compressor starts and runs fine. Did not get before and after readings....no meter....

But the generator starts the compressor with much less bogging down. So I consider the project a success.

Oh and for you guys that are still wondering what was missing on the wiring schematic....it is the line from L1 to the common on the outdoor fan motor.

jtdiesel65

Re: Soft Start for Motors

Hi,

What brand of ac compressor? lennox, trane, etc

I'm trying to fins a compatible soft start for a lennox unit or at least someone with experience with that particular make

I have a 1 ton 48 LRA lennox I'm powering with a couple SW4024 which together are rated for 64 LRA (64 amps for 5 secs). Although the startup is less than a second, the SW's don't handle it well. The inside blower fan is a somewhat small load, but the blower comes on about the same time as the condenser, so I was thinking of adding a soft start to the compressor and a time delay relay to the inside blower....so maybe something like http://www.grainger.com/product/4E233?cm_sp=HIO-_-HIDP-_-BTM_V2V&cm_vc=IDPBVZ12 on the thermostat side.

DanS26

Re: Soft Start for Motors

jtdiesel65 wrote: »

Hi,

What brand of ac compressor? lennox, trane, etc

I have a 1 ton 48 LRA I'm powering with a couple SW4024 which together are rated for 64 LRA (64 amps for 5 secs). Although the startup is less than a second, the SW's don't handle it well. The inside blower fan is a somewhat small load, but the blower comes on about the same time as the condenser, so I was thinking of adding a soft start to the compressor and a time delay relay to the inside blower.

It's a Carrier unit.

The device is smart enough to create a delay between the compressor and outside blower motor start up. So you do not have to add a time delay relay.

The soft start is working great. Also as an added benefit, my lights do not dim any more when the AC kicks on. Best $200 I ever spent!

jtdiesel65

Re: Soft Start for Motors

Hi,

Just got my unit. You mentioned there was a mistake in the wiring diagram? Can you describe it?

thx

DanS26

Re: Soft Start for Motors

jtdiesel65 wrote: »

Hi,

Just got my unit. You mentioned there was a mistake in the wiring diagram? Can you describe it?

thx

See the warning in post #22

See the error described in posts #24 and #25

See the missing line in the diagram described in post #32

Good luck on the install. If you are unsure it is best to have a HVAC tech install. Mis-wiring can result in damage. There's magic smoke in there and you don't want to let it out.

jtdiesel65

Re: Soft Start for Motors

all hooked up:

1.5 ton Lennox unit

advertised LRA= 48a
measured LRA= 25a

with hyper engineering sure-start6:
1st attempt= 6.7a
2nd attempt= 6.3a
3rd attempt= 6.1a

Document says it might take up to 6 starts to obtain max performance. I'll have to monitor it, but looks pretty good as is.

ZoNiE

Re: Soft Start for Motors

You may want to consider an Inverter Air conditioner unit, like a ducted mini split or one of the newer westinghouse units. Compressor is 3 phase, runs on an VFD (Variable frequency Drive) AKA inverter which varies speed with frequency. They never really shut off, but just vary speed based on cooling load. My next units in the house will be these since they are available in the US in 3.5 ton units now in our "typical" config.