I'm fitting a single to 3 phase invertor enclosed in a wall mounted box with ON/OFF switch, etc. on the front panel for the local wood working club to power a wood turning lathe. I was really surprised when I powered it up that there is no indication that the mains power is on. The invertor has a digital display but that's in the enclosure box.
I would have thought a mains ON indicator is mandatory - I'm going to fit one anyway.
Any comments?
Rob
Dredging deep into memory dumps, something stirs: what is obligatory is to fit a contactor switch in the supply to an electric motor.
Maybe one of this groups IEE reg lawyers can confirm with chapter & verse please?
OTOH if the lathe is from a reputable manuf it may already have one on board.
HTH
I think only a power isolator next to the machine (to allow it to be worked on), and an NVR switch on the machine itself are mandatory.
Panic buttons in educational/training environments I don't think are regs, but HSE recommended (so effectively mandatory if you don't want your insurer to have a loophole).
It can be remote, but in that case it must be able to be locked in the off position by a padlock and key provided by the contractor.
The other issue with large motors is overload protection. This is often performed by slow operating thermal trips, but an issue with motors driven from power sources such as generators and inverters is to be sure the source can supply enough power to trip the overload detection. Otherwise you might find your 10HP motor is actually trying to draw 20HP because a bearing is failing, but the power source can't supply this much, so the thermal trips don't operate and instead a more catastrophic failure occurs, such as wiring catching fire.
I tempted to take from the answers which have drifted off to isolating contactors, etc., that the collective doesn't think a power ON light is mandatory - I'm surprised.
As far as isolation and overload are concerned, the 1 hp electronic inverter is powered from 13A socket, which will also be part of the workshop emergency off circuit. I don't at the moment have the manual for this type of electronic inverter but I'm expecting it to be able to cope with motor overload.
Rob
I've always been suspiscious of such lights and, in a workshop, you'll get people who'll believe that the mains isn't on simply because the light isn't on. The only information from any such light is that the light is on or off - nothing else (Two Mile Island).
AFAIR, there's no requirement to show that the supply is live (i.e your indicator). The requirement is instead to be able to demonstrate that a system is safe, and that this can be done by the switchgear, i.e. your "Off" really must mean "Off" and there's no chance of any suprises. So the real safety critical aspect here is a NVR switch downstream of the supply. If you turn the supply back on, you can rely on the machinery not then starting up automatically, even if "left switched on" - thanks to the NVR.
The background to this is (again, AFAIR) due to the inherent unreliability of indicators. Does a dim indicator mean that the supply is safely off, or just that the bulb has failed?
Is that anywhere near Three Mile Island?
Andy
Left a bit.
If a complete core meltdown had occurred...
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