IMO JAGUAR VFD help needed

[asto]

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[birchy]

Well I guess the value we need to know is what voltage range the Orac controller outputs. It sounds like it might be 0-5v rather than 0-10v? At the end of the day, it's just a potential divider circuit, so it should be possible to configure the drive to accept the input and/or use some resistors to bring it within range.

[Swarfing]

Same thoughts Birchy, wondering though if there is output adjustment on the Orac control circuit? if works on step ramp up then it must have fixed voltage divisions. A bit frustrating when the problem is not sat in front of you though?

[asto]

The 2 wires coming out from the Orac's controller (last 2 connectors to the right circled by the yellow line) connect to No. 1-2-3 IN-terminals of the Parajust VFD and these 3 terminals are also circled by yellow line. The third wire is the Shield connected only to the VFD side> Strange but this is how the machine operated all these years.2 wire ends at the controller side but 3 on the vfd side
These three terminals are clearly shown on the attached original Parajust schematic.
K1 is a latching relay fitted on the original machine inverter (that with the large blue capacitor) which makes start/stop easy using just one normally open momentary switch.
so far I have not cleared in my mind how IMO JAGUAR fulfills the requirements for this function. Obviously it is designed a bit differently for start/stop control.This is another problem which I am about to encounter using the IMO in place of the Parajust.

[Swarfing]

Mmmm i wondering if the Orac is using voltage control for the speed adjustment (10v?). the third wire is to ground the shielding of the cable, if it was connected both ends it could cause a ground loop that would cause interference so that is quite normal. Can you check the terminals of the Orac for voltage whilst adjusting the speed controls?

[asto]

...I've done this before and I know from the user manual that for speed control voltage is applied from 0-10Vdc. According to the that inverter specs one can accelarate or deccelarate even by applying an external variable 0-10V source between terminals 4 and 2 of TB! terminal block 4 being negative and of max. 500ma. This is where the wire shield goes.

For Start/stop control it uses 6Vdc

[asto]

Swarfing, the manual extract you see on previous page here explains all this. Just give it a glance if you please

[asto]

Thanks Birchy for the response.
Your idea of applying additional resistors to the network came to my mind as well. But then maybe it won't accelerate to max. RPM . What do you think?

[i2i]

I've seen many of these oracs, and you're quite lucky just to have the inverter fail. In light of the age i would just bin the original controller and go to mach3.

[birchy]

I guess the easiest solution might be a digital potentiometer? It takes a voltage input which controls the passive potentiometer.

Using an Analog Voltage to Control a Digital Potentiometer - Application Note - Maxim