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Industrial ABB VSD Current Draw

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Discuss ABB VSD Current Draw in the Industrial Electrician Talk area at ElectriciansForums.net

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I have specced up a 18.5kw VSD to power a 15Kw pump. On the datasheet ABB ACS580 18.kw its current rating is 38A. Should i spec the MCB and circuit etc to 40A or just to the current draw of the motor (around 28A FLC).
 
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James

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40A is more likely, you are protecting the cable that supplies the vsd.
depending on the configuration of the vsd parameters, it may draw for short periods considerably more than the motor FLC.
the manual for the VSD will have a recommended protection listed.
 

James

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page 159 of the tech. manual suggests it might be a 40A breaker by guessing what the part number means.
I will leave it with you to double check.
 
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page 159 of the tech. manual suggests it might be a 40A breaker by guessing what the part number means.
I will leave it with you to double check.
Thanks for that mate easy once someone tells you where to look. That will probably overload the supply circuit which is annoying. Dont know if you have much experience in speccing up VFD's but would you recommend staying at slightly oversized at 18.5Kw (for a 15KW pump) or can i spec down to the ACS580 - 033A which is rated for actual 15Kw?
 
You should size the VSD to suit the motor so that the motor is adequately protected, yours is a variable torque application not a constant torque one so there is no need to derate the VSD.
 

James

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15kw pump on 15kw vsd is fine.
A 15kw pump only uses that power when running at full load, with a vsd the actual load is going to vary up to max rating you set in parameters.
 

darkwood

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Overspeccing a vsd is sometimes needed for motor duty reasons or even torque characteristics on start up, otherwise just spec the vsd to motor rating.
I had a issue with a geared motor that had slack in chain which we couldn't adjust, it set off normal but the grab as the chain tightened tripped the drive as it saw it as a stall given the 1second of rotation it gave was low demand.
 
As I inferred previously you need to establish whether the application that you are providing the VSD for is a variable torque or a constant torque one.
If it is variable torque then normally the size of the VSD equates to the same size of the motor eg 15kW pump, 15kW VSD.
If it's a constant torque application such as you appear to have then the VSD drive tends to be larger than the motor drive i.e. the larger VSD is derated (usually by the manufacturer) for constant torque applications.
Typical variable torque applications are centrifugal pumps, fans, blowers etc.
Typical constant torque applications are conveyors, positive displacement pumps, agitators etc.
 
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As I inferred previously you need to establish whether the application that you are providing the VSD for is a variable torque or a constant torque one.
If it is variable torque then normally the size of the VSD equates to the same size of the motor eg 15kW pump, 15kW VSD.
If it's a constant torque application such as you appear to have then the VSD drive tends to be larger than the motor drive i.e. the larger VSD is derated (usually by the manufacturer) for constant torque applications.
Typical variable torque applications are centrifugal pumps, fans, blowers etc.
Typical constant torque applications are conveyors, positive displacement pumps, agitators etc.
It is a centrifugal pump so i have went down a model to 15Kw Vsd to suit 15KW motor. That clears things up thank a lot mate.
 
I have specced up a 18.5kw VSD to power a 15Kw pump. On the datasheet ABB ACS580 18.kw its current rating is 38A. Should i spec the MCB and circuit etc to 40A or just to the current draw of the motor (around 28A FLC).
I have specced up a 18.5kw VSD to power a 15Kw pump. On the datasheet ABB ACS580 18.kw its current rating is 38A. Should i spec the MCB and circuit etc to 40A or just to the current draw of the motor (around 28A FLC).
Assume 3-phase.
What are the supply and motor voltage ratings?
 
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