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Vfd Settings


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#1 subrao

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Posted 13 February 2009 - 12:20 PM

I am commisioning an elevator. Drive used is yaskwa F7 and the motor is 380V,50hz,380V rated 4.2Kw at 50hz. Rated current
of the motor is 8.8A A. I fed rated current of 8.8A as given in the name plate. I struggled but the motor does not start when there were 8 passengers. I changed the motor currnt parameter as 10.5A though name plate current is 8,8 A .Elevator started working. I wonder how and why?
I got another doubt If I replace the motor with higher capacity whose rated current is really 10.5 A will it work? which is bettor choice 8.8A motor with feeding of 10.5A or 10.5A motor? What is the mistery behind this?


#2 Shozza

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Posted 17 February 2009 - 10:57 PM

Subrao,

The Yaskawa F7 seems to have a fixed heavy duty overload capacity of 150% motor FLC which limits your starting torque to 150% also. Typically for an elevator you would need an overload capacity somewhere between 175% to 200% and from quickly scanning through the manual it seems that this current limit is not adjustable which reduces your options. You could try adjusting C4-01 which is the Torque compensation gain and see if that helps.
Otherwise replace the drive with something that has a greater overload capacity and greater starting torque.

Also trying to fool the drive by inputting a different motor FLC can affect the protection features of the drive. Try to avoid this if possible as your thermal protection will no longer be protecting your motor properly. Most manufacturers these days allow you to adjust the current limit rather than adjusting the motor current itself which results in the thermal model still being based on the actual motor FLC.

If the motor can start the elevator by inputting a higher motor current then it is obviously capable of carrying the load. It seems that the drives is the limiting factor.

Best regards,
Shozza

#3 pankajhal

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Posted 16 June 2009 - 12:25 PM

U r feeding rated current details in vfd. Motor rated current is 8.5A so at the time of loading motor load current is more then 8.5A due to overloading or voltage variation nd ur vfd is set to 8.5A so it may trip. thats y when u increase current setting arround 10A it starts working cause load current is near to 10A. one of the reason is that the motor is overloaded u have to increase the motor capacity. Go for higher KW rating motor more than 4.2 Kw dont interrelate it with motor current hope it will be ur solution.




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