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Old 07-07-2018, 09:15 AM   #8
sdowney717
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City: Seaford Va on Poquoson River, VA
Vessel Name: Old Glory
Vessel Model: 1970 Egg Harbor 37 extended salon model
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Quote:
Originally Posted by C lectric View Post
Soft start often means reducing voltage and then ramping it up to get a motor turning. Or it could be PWM meaning a full voltage but short pulses of increasing duration to develop full torque Often refrigeration units are under full or near full load from the instant they start meaning a soft start won't get them rolling untill the amperage is fairly high. Sometimes work and sometimes not.

That grumble may not be the motor turning but the motor stalled. They do make a noise if they are energized but cannot rotate because they can’t get enough power to do so.

Often touted as an answer is a "Hard Start Capacitor" for units intended to be started on barely adequate for the inrush current generators. They do work. THese bigger capacitors create a stronger torque instantly, almost, to get that motor moving by increasing the phase offset between the run and the start windings. The stronger the torque the faster the motor will start thus getting out of the very high inrush current part of the startup much more quickly.

That will have a huge bearing on what the breaker does. A very high overload of very short duration can often be handled although it may cause the generator itself to bog somewhat. As long as the high inrush is fast enough your A/C and gen. MAY be ok.

Just watch the total current output as I'll bet it shouldn't be more than 75% to 80% of the generator's output capacity. Find out what the generator continuous rating is as it is often less than the so called size name would indicate.
I contacted Tecumseh about about my Cruisair system and gave them the compressor number

He said a range of start capacitors were specced for the model number, my plan is if it goes out, I will put in the 88-108 mfd to reduce the amp draw at start the most it can bear.

Code:
We have several starting capacitors released for this model.
 
21-25 mfd
47-56 mfd
72-88 mfd
88-108 mfd
So most likely a higher start capacitor can be used, if the unit came with one, or add the hard start kit to do same thing.
Quote:

Subject, correct value for run capacitor compressor # AK147AT-009
1
Lattuca, John <xxxxx@tecumseh.com>
Wed 6/25/2014, 12:00 PM
You
Inbox
Scott:

Regarding your question on the range of starting capacitors, we sometimes run tests per customer starting requirements, which results in the release of various microfarad ratings.

Your compressor should start easiest with the largest rating possible (i.e. 88-108mfd/330V).

Normally, the acceptable tolerance on run capacitor ratings is +/- 10% (i.e. 31.5 mfd to 38.5 mfd).

If the compressor motor is optimized using the 35 mfd run capacitor, using a 30 mfd run capacitor should not change the compressor amps much.

Use the 35 mfd run capacitor and the 88-108 mfd starting capacitor to maximize starting ability.

The approved 60Hz voltage range for your compressor is 115V +/- 10% (i.e. 103.5V to 126.5V).

If you have additional questions, please contact us.


Best Regards, John

Scott Downey
Thanks for that info.
It currently has a 30 mfd run and need a new one because it popped.
So I will get a 35 mfd

It has a 47 to 56 start right now and it starts well before it blew the run cap.

Why such a big range on start caps?
Which one will make it start the easiest?

I read a lower value run cap makes the compressor draw more amps.
I wonder why it had a GE 30 mfd in there. It is old run capacitor very tall.

Numbers on it are
GE
72F5046
30uf 370v
6577651

What combination of capacitors do you think would be best on a marina's marginal power? Or it makes no difference?
Sometimes the voltage drops below 110.

Lattuca, John <xxxxx@tecumseh.com>
Tue 6/24/2014, 4:24 PM
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Scott:

The run capacitor is 35mfd/370V.

We have several starting capacitors released for this model.

21-25 mfd
47-56 mfd
72-88 mfd
88-108 mfd

The relay released for this model has a pick-up voltage of 170-180V.

Oil Charge: 17 ounces.

Oil Recharge: 13 ounces

If you have additional questions, please contact us.


Best Regards,

John Lattuca
Senior Engineer - Technical Specialist
Tecumseh Products Company
5683 Hines Drive
Ann Arbor, MI 48108
800.211.3427 toll free
734.585.9471 direct
734.352.3771 fax
xxxxx@tecumseh.com
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