Motor control through invertor

[flyingsparks]

I have been asked to fit an invertor to a 3 phase motor for speed control. The invertor is currently installed on another motor which is no longer required. The new motor is smaller with a 3.35A FLC and the invertor has a max output of 7.6A.
The invertor being used is this one:

http://datasheet.octopart.com/MMX34AA7D6F0-0-Moeller-datasheet-8360488.pdf

Would the contactor and overload be fitted before or after the invertor? All starting is manual at the invertor/starter not controlled by other means.
Does anyone know if paramaters need setting up on this invertor, as we can't find a tech data on this.
Thanks

 

[Echo the husky]

Every inverter I have fitted has built in overload protection and is set up within the inverters settings. starting and stopping is by connecting buttons to the inverter, speed control by a pot wired to the inverter, or via the buttons on the inverter. A local isolator will of course have to be fitted. Looking at the link you posted it has all these features.

Yes you must set the unit up to match the motor and the application the motor is being used in. You should hopefully be able to get a copy of the installer manual by contacting Eaton.

 

[flyingsparks]

Every inverter I have fitted has built in overload protection and is set up within the inverters settings. starting and stopping is by connecting buttons to the inverter, speed control by a pot wired to the inverter, or via the buttons on the inverter. A local isolator will of course have to be fitted. Looking at the link you posted it has all these features.

Yes you must set the unit up to match the motor and the application the motor is being used in. You should hopefully be able to get a copy of the installer manual by contacting Eaton.

Cheers Freddo, as I thought regarding the overload protection and paramaters needing to be set. Finding the instructions is going to be the interesting part I think! Do you need a contactor then if using an invertor? Obviously there will be local isolation too. Cheers.

 

[Echo the husky]

I've never seen a contactor used with an inverter as the inverter will do all the switching. The manual is on EATONs website here, it tells you how to change the critical settings but not what each setting is for

Edit found the other half of the manual here!!

Edit II those links don't work so you will have to find it here under switching protecting and driving motors.

 

[flyingsparks]

Thanks mate I will have a read through that!

 

[Echo the husky]

No problem. You'll read through that manual in no time, it's only 287 pages

 

[ericmark]

The contactor is always before the inverter. In the main it has one job only, the emergency stop. The rules will not allow normal electronic (there are some special exceptions) isolation for estops so that is all the contactor is there for. Often you required two contactors independent one large one on main incomer and the control circuit. Using solid state contactors and inverters removes the second isolation so contactor is added.

Most inverter instructions tell you never to have an isolator of any kind after the inverter. And as said overload is a function of the inverter.

Of course always exceptions to the rule, some old inverters change single to three phase and you can run multi-motors off same inverter some being rotary inverters but these are rare.

 

[Simon35]

O

I have been asked to fit an invertor to a 3 phase motor for speed control. The invertor is currently installed on another motor which is no longer required. The new motor is smaller with a 3.35A FLC and the invertor has a max output of 7.6A.
The invertor being used is this one:

http://datasheet.octopart.com/MMX34AA7D6F0-0-Moeller-datasheet-8360488.pdf

Would the contactor and overload be fitted before or after the invertor? All starting is manual at the invertor/starter not controlled by other means.
Does anyone know if paramaters need setting up on this invertor, as we can't find a tech data on this.
Thanks

How will you provide an emergency stop function, if your risk assessment shows it is required? It may be that the existing contactor was used in as part of a safety circuit.
You dont need a local isolator, just a means of isolation, which may be the inverter panel.

 

[bernardgreen]

Check the manual for any "minimum time before re-start " or similar restriction on re-powering the invertor after power has been removed. Some invertors have this restriction of having to wait as much as a minute before restoring power. One type had a surge limiting resistor in the input and this failed if power was re-applied while it was still hot. Every time the machines stopped on the safety interlock there was a minute delay before it could be restarted. When an impatient operator re-set the safety interlock too early there was a good chance that one or more of the invertors would fail. The cure was fitting a larger resistor. on over 100 invertors.