Hello.
I have am trying to set up a vfd to power/control a 5 horse three phase 220 v motor on a lathe in a single phase shop.
I'm trying to determine the best place to have overload protection (say within VFD vs conventional thermal relay) and
to thus determine what features I have to have in a suitable VFD.
The lathe has separate contactors for direction and these go into a thermal relay to drop input current if an overload occurs.
VFD use will alter at least the directional control part of this.
Some VFDs say not to put any kind of contactor after the VFD.
Given this I assume overload protection is to be done via
(a) detting a limit in VFD configuration so it knows how big a motor it is running.
(b) trusting the VFD to limit or zero the output current appropriately.
Alternatively one could rig the overload condition to interrupt the power into the VFD (I suppose).
Some VFDs don't seem to let you set a max current and presumably infer that from the HP rating of the VFD.
I'm guessing those should be avoided.
I'm trying to decide whether VFD based overload protection is adequate and if not what is the best way to
achieve it.
Thanks,
f
I have am trying to set up a vfd to power/control a 5 horse three phase 220 v motor on a lathe in a single phase shop.
I'm trying to determine the best place to have overload protection (say within VFD vs conventional thermal relay) and
to thus determine what features I have to have in a suitable VFD.
The lathe has separate contactors for direction and these go into a thermal relay to drop input current if an overload occurs.
VFD use will alter at least the directional control part of this.
Some VFDs say not to put any kind of contactor after the VFD.
Given this I assume overload protection is to be done via
(a) detting a limit in VFD configuration so it knows how big a motor it is running.
(b) trusting the VFD to limit or zero the output current appropriately.
Alternatively one could rig the overload condition to interrupt the power into the VFD (I suppose).
Some VFDs don't seem to let you set a max current and presumably infer that from the HP rating of the VFD.
I'm guessing those should be avoided.
I'm trying to decide whether VFD based overload protection is adequate and if not what is the best way to
achieve it.
Thanks,
f