Inverter

At work I came across thermistor protected motors. The thermistors were 600 Ohms and went high when over temperature. They were extremely unreliable and would go open circuit and hence the control gear would switch off the motor and the TV transmitter would fall to reduced power!!

Frank

Motor driven TV transmitter? Was the motor used to drive the Nipkow disk?

Russell;

Hi all,

Well it looks as Ian Phillips is correct about the wiring of the pot .
And there is a program to cater for this .
In the picture below you will see the wiring diagram for the 10k pot (mid picture L/H side )
As drawn the pot is connected across the VR (10v) and the ACM terminal and the wiper connected to the V1 terminal .
If I go into program 70 I can change from voltage sensing to current sensing and the unit will work only when voltage sensing is set when configured like this but 0- full speed achieved in the first 1/3-1/2 of the pot travel as described in my previous post .
So I decided to try disconnecting the ACM terminal and connecting the AI terminal instead and changed the setting in program 70 to current sensing (0-20ma) and away it went ! I now get a speed change over about 75% of the pot travel .
I'm not sure what the little circle is that is connected between the ACM and AI terminal and the mostly useless manual does not elaborate on this either , maybe it is Chinese for optional !

The terminals that were marked incorrectly are the ones at bottom left SPH was ok but SPM &SPI were reversed or the printing in the manual is wrong , I have set these up for emergency stop and fwd /rev jog .

Ian

If there isn't a setting to change the voltage sensing input voltage range you can just insert a 10 k fixed resistor between the pot and VR(+10V).

Russell.

Ian

The main thing is that you have got it working but I still feel its not quite right. I would have expected that all of the pot travel would be used rather than the 75% or so you mention.

My interpretation of the terminal markings in your diagram would be:

VR = Reference Voltage
VI = Voltage In
ACM = Analogue Common
AI = Analogue In?

The first three, I would be 100% confident about but only 95% for the AI.

The unmarked circle represents whatever the Chinese says! Its most likely an alternative input for current control. Since the circle is only 'two terminal' it will need to be driven by a floating current device but some tests with a meter should be a able to diagnose what it happening there. Ironically they do show the VFD internal wiring for the digital outputs but not the inputs.

Another thought, In this wonderful web world, I wonder if there an method of inputting an image of the Chinese characters and getting it translated online?

What is the brand name of these inverters, I think I will ovoid them! (Unless they are a bargain!)

Ian P

Item number 260937540695 on eBay .....

The symbols directly under the motor symbol, next to the switch, read "electrocute caucasians now, with this button"

(I think)

Sorry I don't know more.

AI = Amps (current) In ???

Russell.

Doubtful really, its unlikely that would use the same letter as they correctly use for analogue.

'I' is the symbol for current really, but that would add even more confusion here. The eBay listing does not actually clarify anything either but Ian S has got it working so its not important now.

Ian P

Hi all,

the AI terminal as explained in the manual is Analogue current but it could be labeled incorrectly also and could actually be the ACM terminal instead .

The Chinese writing under that little circle may be a good psychiatrist to call once you have lost what was left of your sanity trying to work out what the circle means !

In program 70 you have 4 settings :

1) 0-10v

2)0-20ma

3) 2-5v

4)2-20ma 10v stacked 

if the pot is connected to the ACM terminal numbers 1&3 operate

if the pot is connected to the AI terminal numbers 2&4 operate.

Other than a crappy manual  the unit is worth the $250 au and cheaper for smaller units .

thanks for all your help with this issue  also  .

Ian

Edited By SLOTDRILLER on 19/11/2013 18:56:31

Can any of you electrical whizzkids give me a bit of advice.

I have just bought what I thought was a 2.2kw (new but second hand) 3 phase motor to be driven by a 2.2kw VFD. It turns out that the motor is actually a 3 kw. You can obviously guess the question. Can I run this motor satisfactorily from the 2.2kw VFD. I'm guessing I can as the motor will never run at it's full rated output.

Cheers

Paul