Vfd

They dont usually have any internal fusing.

Inrush current limit is usually done with a thermistor feeding the bridge rectifier, bus caps.

If you disconnect the motor from the outgoing terminals, is the error still present? If so, then the vfd is in need of repair.

What make/model is it?

Edited By John Rudd on 27/01/2019 17:15:40

The most likely failure point for electronics is when powering on.
I have Siemens VFDs which have been working for over 15 years and were ex-industrial when I bough them, I don't power off VFDs.

I have a TECO VFD which failed after some time in service; I returned it to the supplier who "replaced the fuse".

I s there a consensus for leaving VFDs powered on?

Use the VFD Stop rather than turning the speed control down, best case no difference, worst case your potentiometer calibration is off and you overheat something. 

When I referred to powering off I meant just that. 

Edited By Nick Hulme on 27/01/2019 20:30:24

No, if they're properly designed turn on and turn off at the start and end of the day isn't an issue.

Andrew

Industrial VFDs are powered up 24/7. A maintenance manager who was not an engineer insisted that 600 robots were powered down during non production hours to save on electrickery, on power up a high level of failures were experienced which was very expensive in parts and time to fix the breakdowns. Equipment in good condition will not have a problem surviving a power cycle but it will expose anything that is not in its best working order. The power saving trial was soon dropped as the part failure and repair time was not worth the minuscule power saving. I suspect the attrition experienced would have improved as the parts that were weak were eliminated but after spending ten of thousands on spare parts the trial was abandoned. Personally I would prefer to power my workshop down as it is unmanned most of the time and as things do not always fail safe I feel more comfortable minimising the risk. I would rather have a device failure than a fire in my workshop.

Mike

I have four VFDs in the workshop and each takes around 15 watts on standby.

I reckon that’s about £70 a year 😳

Edited By kevin large on 29/01/2019 16:00:13

2 little round things like a lolly on 2sticks

Could be NTC inrush current limiters - these are a highish resistance cold & heat up when the current to the rectifier & capacitors flows (at a reduced level, due to the resistance). As they heat up, the resistance reduces towards zero. Their purpose is to "softly" charge up the capacitors on start-up & some types look as you describe.

I have had a couple (in small power supplies) that have gone pop & failed open circuit, so no current flows. There should be a part number on the side of the device - hopefully still readable if it is burnt - that should allow identification & replacement. A search for NTC inrush current limiters will get hits to Franell, Mouser, Digikey etc.

HTH

Nigel B

t lighting also)+1 for using an inverter. I put a single phase motor in mine and had the power table reconnected for single phase. The main motor was never satisfactory and made a most unpleasant hum which resonated round the workshop with nullls and maxes in certain locations of the room.

Changed back to 3 phase with VFD and it's been a revelation - silent and so nice to get the exact speed you want. I have a rotary lever with ball end on the front panel and can adjust this with my knee while operating the feed handles. Magic!

I did just have to rewire the panel to separate the single and three phase circuits ( mine has Lovolt lighting also)

John

Edited By JasonB on 30/01/2019 13:17:58