VFD output cable size

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hhsting said:
From Overcurrent protection??


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The drive protects the cable and or the motor from overcurrent/overload. Think of it as the overload block on a standard ATL starter. Only way better. That does not mean that you cannot screw up by setting the parameters incorrectly. No different than using the overload twice what they should be.
 
ptonsparky said:
The drive protects the cable and or the motor from overcurrent/overload. Think of it as the overload block on a standard ATL starter. Only way better. That does not mean that you cannot screw up by setting the parameters incorrectly. No different than using the overload twice what they should be.
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I dont understand how drive protects from overcurrent protection? Their is no overcurrent protection in vfd and if their is one provided does that not protect the drive not the output conductors?
 
hhsting said:
I dont understand how drive protects from overcurrent protection? Their is no overcurrent protection in vfd and if their is one provided does that not protect the drive not the output conductors?
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The drive knows how much current is being fed to the motor. Most drives you can see this in the display. It's a fairly simple mathematical calculation to do the I squared t calculations that the heaters do mechanically in a typical thermal overload.
 
hhsting said:
I dont understand how drive protects from overcurrent protection? Their is no overcurrent protection in vfd and if their is one provided does that not protect the drive not the output conductors?
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Like Pton said, think of the drive like a variable overload block where you can set the amps from lets say 10-20 amps. Even if you are protecting a motor that has a FLA of 10 amps and you run 14AWG you could still crank that thing up to 20 and then your wire wouldn't be protected. Same thing with a drive but you don't have a physical overload block it is all in the drive. You still set the over current protection for that motor/wires. You still have to fuse your drive for the correct short and ground fault protection.
 
Krusscher said:
Like Pton said, think of the drive like a variable overload block where you can set the amps from lets say 10-20 amps. Even if you are protecting a motor that has a FLA of 10 amps and you run 14AWG you could still crank that thing up to 20 and then your wire wouldn't be protected. Same thing with a drive but you don't have a physical overload block it is all in the drive. You still set the over current protection for that motor/wires. You still have to fuse your drive for the correct short and ground fault protection.
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So lets say you have fuse in the vfd integral does that protect the output conductors or not?


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Not needed. Here is an article of VFD output circuits.
www.linkedin.com

Why is there no short circuit protection for VFD (Variable-frequency Drive)?

Short-circuit protection is a function of the device connected between the power supply and the load, which can effectively disconnect the short-circuit point from the power supply when a short-circuit occurs on the load side. A device has a short-circuit protection function, so it must have a certa
www.linkedin.com www.linkedin.com
 
hhsting said:
I dont understand how drive protects from overcurrent protection? Their is no overcurrent protection in vfd and if their is one provided does that not protect the drive not the output conductors?
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Most drives have had listed motor overload protection built in for a couple of decades now.
 
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