petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
We have been using these fuses for some time now as a cost saving measure. The blown fuse indicating feature (ID) seems to be standard now.
It turns out there is a bit of a quirk with this feature though. We had a VFD that blew a fuse but the fuse did not indicate it.
It turns out that the ID feature is not always activated as fast as a downstream device can turn off so the indicator is not always going to be present if you blow a fuse on a device that can shut off very fast. Littelfuse said this could be a VFD, a fast circuit breaker, or other very fast device.
And you can get fooled because the indicator is in parallel with the fuse element, and the downstream device shuts off, the very high impedance of the indicator that has not tripped will make the correct voltage appear on the device terminals.
If anyone wants the fax we got from Littelfuse, feel free to PM me.
It turns out there is a bit of a quirk with this feature though. We had a VFD that blew a fuse but the fuse did not indicate it.
It turns out that the ID feature is not always activated as fast as a downstream device can turn off so the indicator is not always going to be present if you blow a fuse on a device that can shut off very fast. Littelfuse said this could be a VFD, a fast circuit breaker, or other very fast device.
And you can get fooled because the indicator is in parallel with the fuse element, and the downstream device shuts off, the very high impedance of the indicator that has not tripped will make the correct voltage appear on the device terminals.
If anyone wants the fax we got from Littelfuse, feel free to PM me.
