Bypass failure Soft Start

[LIAM C]

Can someone please lend some guidance!

I have a 30KW motor that drives a fan, it’s started by a 3RW3047-1BB14 soft starter.

Settings are as follows:
- Class 10
- Motor Current 63A
- Current limit 5 x/e
- Ramp up time is 10 Seconds
- Starting voltage is 70%
- Ramp down time is 5 Seconds

During start up I’m reading an inrush of about 250-275 Amps and about 220 Volts before it’s cutting out and displaying ‘Bypass Failure’. I have tried adjusting the soft start settings but getting the same result.

If I detach the belts that drive the fan the motor starts up no problem reaching its 420v and running at about 18A.

The motor and soft start are both new as the bearings had collapsed in the previous motor.

I’ve also checked all of the bearings and drive shaft on the fan side, everything is free.

Any ideas?

 

[jraef]

At an initial voltage of 70% and a Current Limit setting of 500%, you are basically attempting to start that fan DOL, so the Bypass is going to try to turn on almost immediately. But because the bypass contacts on that unit are not rated to carry starting current, it is not allowing that to take place.

Lower your Starting Voltage to about 20%, lower the Current Limit to about 3x.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[Parchie]

@LIAM C,
Your current limit sets the upper limit to which the SS stops to ramp the voltage until the motor speed shall have spun faster and the current has dropped below the limit. Your ramp time elapsed but the motor speed hasn't reached the safe transition point for a full voltage hence the error message. Suggest to lengthen your ramp time.