Sizing of Braking Resistor
Sizing of Braking Resistor
(OP)
I'd like to check braking resistor sizing of VFD. What philosophy is used in sizing braking resistor, i.e. how to size braking resistor.
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Sizing of Braking Resistor
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RE: Sizing of Braking Resistor
RE: Sizing of Braking Resistor
So, if your only purpose is one stop per hour or e-stop service only, you can figure your braking kw and then buy a resistor rated one-tenth that wattage.
Saves a little money.
RE: Sizing of Braking Resistor
RE: Sizing of Braking Resistor
First is the rotational kinetic energy that you want to dissipate. The resistor has to be sized large enough power wise not to melt down when this energy is dumped into it.
Second is the current capability of the VFD. The manufacturer will either give a maximum current or minimum resistor size in the specification. This is used to find the ohms of the resistor.
RE: Sizing of Braking Resistor
go here, if you buy from a vfd manufacturer, they usually resell from these guys. Used to be called IPC.
good info on site
RE: Sizing of Braking Resistor
As already pointed out, the VFD manual will typically inform you of the resistor ratings if the brake chopper is integral.
RE: Sizing of Braking Resistor
Continuing on the theme of inertia, if you try to slow the motor down too quick it can lead to VFD trip due to overvoltage on the DC link.
I agree, contacting the VFD manufacturer is the way to go but they do need some specific info on the load that you are trying to pull up. It is not a trivial calculation you need velocity info of the load and masses.
Chris Devine
www.icande.com.au
www.redbusbar.com