Dear All,

I am developing a u-controller based 2 HP Submersible pump starter. Could any one guide me to the exact starting sequence for a CSCR motor?

From what I learnt, the 'Start capacitor-winding needs to be energized first for about 500ms through a Relay and then the actual motor winding needs to be energized through the contactor.'

But I was not sure about the initial surge current drawn by the 'Start capacitor/winding.' As this dictates the choice of the relay used.
Could any one help with this?

My email ID is: scorpiokid81 [at] gmail.com

 

Thyagu... a submersible motor is not equipped with an internal-contact associated with the starting-capacitor found in single-phase motors. Hence the need for externally-mounted relays.

You need two relays, a 'Run' relay and a 'Start' relay. They are energized simultaneously without an intentional delay. When the motor has achieved full speed, the 'Start' relay is de-energized, disconnecting the Starting Capacitor'!

If you need a schematic or connection diagram, contact me off-list!

Regards, Phil Corso

 

Hi Phil,

Thanks for the information.
I could not find your email-ID to ask this question offline..

What should be the Relay Contact-current-rating to be used in the path of powering the Start-capacitor ?

In other words how much current does the Start capacitor draw for the time till the speed picks up and it is disconnected ?

Is it greater than 5 times of the steady-state motor current ?

 

Thyagu... it is (cepsicon [at] aol [dot] com}

Phil Corso