Inverter

This seems to vary between makes. My ABB unit has to have the maximum rated motor current set. That enables you to safely use a motor of lower rating than the inverter. My Mitsubishi unit doesn't have that setting so if you overload the motor you may have problems however the same applies running the motor off a normal three phase supply.

The "automatic torque boost" function only affects start up so is unlikely to cause a problem running small motors on powerful inverters.

Russell.

The smaller Teco-Westinghouse devices have no current settings either.

My Jaguar Cub allows you to set the motor parameters off of it's rating plate, and uses these to monitor over current etc. and to calculate when the motor is at risk of overheating through slow running.

Neil

Sounds good what happens when it gets to the point where it thinks the motor is at risk does it shut it down?

If you fit additional cooling to your slow running 3 phase motor to counteract the temp rise from lack of airflow can you override the setting?

Regards

Paul

I don't understand how it can do that as motors vary in their ventilation characteristics. I am using Magnetti Marelli (sp.?) motors that are designed for inverter speed control and have a higher airflow than normal. I guess it must make some assumption about motor characteristics.

Personally, I just feel the case temperature by hand occasionally if slow running for extended periods.

Russell.

Hi Paul,

I haven't tried overheating the motor to see if the inverter shuts it down. But I had a small accident that stalled the lathe, and the inverter immediately shut off the supply to the motor so no harm was done.

Russel, I do as you do, feel the case temperature by hand and if I feel the motor is getting hot, either shut it down or let it run at high speed (without load).

Thor

The VFD monitors the resistive component of the winding. The temperature coefficient of copper is 0.39% per degree, or about 20% change for 50 degree increase - easily detectable.

It issues a warning (which you can set to trigger an output) and if you carry on it stops the motor and gives an error code.

It makes assumptions about the motor's 'thermal constant' which is given in seconds. Like many system variables this is set to a typical value and can be reprogrammed (presumably by those with lots of time on their hands or professionals setting up VFD/motor pairs for specific applications).

Neil

+1

And if you can smell burning insulation resin it's also time to give it a bit of a rest

Thor,

If I occasionally "jam" the Teco driven Bridgeport it does exactly the same but then it takes a complete shutdown of the inverter for it to recover, iv'e often wondered if this shouldn't be more of an E-Stop type event?

Paul

Yes know what you mean some of the manuals/menu's are like wading through treacle.

So to fix this you could:

Fit a temp sensor on the motor wired to say an Arduino to do two things:

Once it hits "X" temp switch in an external fan you have secreted on the motor

If temp still rises then trigger an E-Stop on the inverter but leaving the external fan running till the temp reaches an acceptable/normal level.

Paul

My motor has a temperature sensor built in and the inverter knows how to use it (if I can give it the spec) but I don't know the spec of the sensor, beacuse I bought a vanilla motor and the sensor seesms to be an unexpected extra, not mentioned in the motor manual

Neil

That sounds reasonable, however it means that it is measuring the actual temperature not "calculating when the motor is at risk of overheating through slow running"

Russell.

Hi John,

The VFD is a HUANYANG HY03D023B 3KW 220V.

From the manual the model number equates to : HY = TRADE MARK

03D0= 3KW

B = SOFTWARE VERSION.

I have had a scout around on a few different forums and there seems to be a few inverter units not working straight out of the box and I had to go through the entire list of parameters to ensure the factory settings were set correctly , the main settings that were wrong were frequency settings and I would think they were set for the small 3ph spindle motors that they sell.

I suppose that for the money one can't complain.

Ian

You may find there is a mode where you can step through settings (but not edit them) that only displays those that have been changed from the default in the manual. I solved an issue (caused by me) with mine this way.

Neil

Sslotdrill/Ian,

I have the same units, I'll check what the programmed parameters are and get back to you....

I struggled at first when I tried programming mine but have a good idea on these units now...

Ok here's what parameters are programmed in mine to make it run at 75 hz.....( I have a 1.1kw motor running at 1400-ish rpm its a standard 4 pole motor and I run it at 1.5 times speed)

Parameter

Pd000=0, parameter lock

Pd001=1, Source of run cmd

Pd002=2, source of frequency

Pd003= 75.0, main frequency

Pd004= 50, base freq.

Pd005= 75, Max op freq

Pd006= 2.5, intermed freq

Pd007= 0.5, min freq

Pd008= 220, motor volts

Pd023= 1, Rev. rotation enable

Pd024=1, STOP ....dont matter...

Pd025= 0, start mode

The setttings below are for running from the i/o terminals.

Pd044=2,

Pd045=03

Everything else is set as factory default, so should be ok....

Any probs give me a shout..

Thanks John I will have a look through my settings and see if there is anything amiss .

I know that PD004,006,007&008 are the same as yours .

Ian

Ok I have gone through the entire list of program settings again , had a play with the wiring of the pot , tried a logarithmic and linear pot and tried the 5v ref voltage instead of the 10v but nothing has changed .

So it was back to the internet for a good search and on one forum there was a suggestion of using 2 pots in series so I gave that a go and it worked .
So the 10v ref now connects to the wiper of a 1mohm pot (pot1) and one of the outer pins of pot 1 connects to one of the outer pins of the second pot a 10komh unit (pot 2 )- the other outer pin of pot 1 is not connected . the other outer pin of pot2 is connected to the ground terminal and the wiper of pot (2) goes to v1.

So how do you set it ?
Easy , turn on the vfd , press start with both pots wound fully clockwise and if all is well you should only get the lowest speed or some humming from the motor .
If the machine spins up to speed try winding the 1mohm pot the other way and the speed should slow to a stop or your lowest speed setting as per the internal programming .
Now you want to check if the other pot is wired to give a speed increase as you turn it clockwise so wind the 1mohm pot back a little to get say half speed and see which way the 10kohm pot has to turn to get a speed change , if it slows down when turned clockwise you need to switch the connections on the two outer terminals of this 10kohm pot (leave the wiper or middle connection alone )

If if the 1mohm pot is backwards switch the outer terminal only as the 10v ref stays on the middle connector .
So now we have sorted that out wind everything clockwise and start up the vfd again then simply wind the 1mohm pot anti clockwise until you just get the maximum frequency as set in the programming and you should find that by turning the 10kohm pot anti clockwise the speed slows over the entire travel of the pot

Sounds complicated but once I tried it I found it simple and the 1mohm pot is now mounted in the bottom of the vfd unit with a dial type knob and a reference mark to re set it if needed .

But wait there's more !
Now say you have your max frequency set at 75hz for example but most of the time 50hz is all you would use you simply turn the 1mohm pot to this setting and you have a maximum frequency of 50hz without changing any programmes ! If you want to go back to 75 hz simply wind it back to get what you want on the vfd display .

So the 10kohm pot is your fine speed control and the 1mohm pot is your course speed control .

Apologies for the long winded-probably confusing post and for hi jacking the OP somewhat .

Ian