Help! How does one determine capacitor values for a capacitance start motor. The motor had 2 capacitors and both were removed by person unknown.

The motor name plate contains the following data only

Manufacturer: Mindong Electric Corp., China,

Type: YC132SB-4, 5 HP, 28 Amp,220V, 60 HZ, INS.CL.B,1750 RPM,

SN 3183,

I've contacted the manufacture and they are telling me the capacitor information should be on the name plate which it isn't. Your assistance would be greatly appreciated.

Len

 

AS you know the reason for using the capacitor in series with the starting winding of the motor is to produce a leading phase shift between the current and voltage of the starting winding.the larger the capacitor the higher is the phase shift and the greater is the starting torque.So actually the value of the capacitor depends on how much toeque you need at the starting.To calculate the exact value of the needed capacitor you need also to know the inductance and resistance of your sarting winding which you don't have.

I used some assumptions for your motor and came up with a value of aboat 500 micro farad for your capacitor.As I told you you can start even with a smaller value.If you saw that your motor does not run you can increase your capacitor.Be careful to take the voltage of your capacitor higher than 400 volts.

Good luck
([email protected])

 

Responding to Len Harvey's 11-Aug (12:42) query... you mentioned the motor had two capacitors!

If true, then be aware that one is conected permanently, while the other is switched out of the circuit at a certain speed.

The capacitor that is switched off is the electrolytic type, while the permanent one is oil-filled!

I suggest you search the Control List Archives for similar topics!

Regards, Phil Corso, PE ([email protected])

 

Further to my earlier response to Len Harvey… can you determine how many leads were attached to the missing caps?

I ask this because if an old design then there could be a safety issue. A clever circuit was used to substantially increase effectiveness of the start-cap. It consisted of an auto-transformer having a 5:1 turns-ratio. When connected to, say, a 20uf cap, its effective value was increased 25-fold to 500uF.

Regards, Phil Corso ([email protected])

 

Both caps have 2 leads.

 

To the person that tried to reach me off-list:

Your e-mail was mistakenly identified as spam!

Please try again!

Phil Corso, PE ([email protected])