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| John Rudd:
Let me just clarify one thing here about my installation....... I'm running a 1.1kw 3 phase motor via an Invertek 1.5kw inverter. There is nothing between the output of the inverter and the motor, this is directly wired with 2.5mm2 tri-rated wire....run in conduit. On the input side, I used the existing wiring that fed the run winding of the original motor. This supply goes via the nvr switch, as did the start wiring( subsequently removed..) The nvr is interlocked with the chuck guard( although I'm not actually using it, the wiring has been removed) and the pulley cover atop of the machine. Normal Stop-Start of the mill is taken care of via the Fwd-O-Rev switch that sits along side the speed control pot. These inputs are wired to the control terminals on the inverter. In the event of a supply interruption, the machine power is cut, in the event of an emergency the power is also cut, this is the job of the nvr switch....it is hard wired and is not subject to the software of the programmable inverter, this is in line with standard industry practise... So, there you have it...hopefully clear and simple.... |
| philf:
Hi Phil, I agree that probably all inverters have a built in NVR function particularly when using the inverter's inbuilt start button. I use this facility on my bandsaw with a Mitsubishi Freqrol inverter. From memory I couldn't do this on my lathe because I wanted to use the fwd/reverse inputs. Earlier you mentioned "In industry it is not permitted to derive safety interlocks from electronic data, it must be actual switches." At the hydro scheme I'm involved with there is an on'off switch on the control panel for each of the two Archimedes screws. We recently had a problem where the PLC got stuck in a loop (bad programming I think) and one of the screws started even though it was turned off on the front panel switch! On investigation it turns out that the switch just connects to a PLC input! I'd be interested to be able to quote to the manufacturers the relevant regulation(s). I was going to change the switch over to a lockable switch but that's of little use if the PLC ignores it under certain circumstances. Cheers. Phil. |
| appletree:
Hi John I was not dissing your install at all I was just trying to suggest that inverters are best not having the supply disconnected as a method of control . We are both happy with the way we have chosen to wire and control our installations so all good. So I wish you all the best with the remainder of the tweaking of your machine. No doubt your are looking forward to its completion and the next phase, making things with it. Phil |
| John Rudd:
--- Quote from: appletree on January 02, 2017, 08:57:24 AM ---Hi John I was not dissing your install at all I was just trying to suggest that inverters are best not having the supply disconnected as a method of control . Phil --- End quote --- I'm sure you were not.....and I dont advocate the method of stopping an inverter by hitting the nvr switch....although when I'm finished for the day, I switch the mill off at the socket....not while its running... :zap: As an aside, the inverter will self protect ( depending in the make and the software), if it detects an undervoltage it will lockout....unless someone sets the software to restart afterwards.....not necessarily a good thing... As you say, if we are all happy with the way our machines are wired and operate who cares? :) Well back to tweaking... :dremel: |
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