IE3 vs IE4 motors - price, availability

[MartinLe]

I'm writing a tender that wil include a handfull of motors, 3-11kW that will run practically continuosly. My question is if it makes sense to specify IE4 motors (default is IE3). Is the cost difference significant, are there concerns in swapping one for the other?
So if the supplier would normally work with IE3, if we demand IE4 they could not deliver.

This is for Germany where AFAIK the better efficiency classes have less market penetration than in the US.

 

[micalbrch]

Everybody can supply IE3 motors but only a very few manufactures have a cpl. range of IE4 motors, especially for the small sizes. If you do not have a manufacturer preference, I would not specify IE4 motors because it will be significant price adder. Companies like ABB, Siemens and VEM have IE4 motors but other (much cheaper) manufactures don't. And the efficiency difference between IE3 and IE4 in the range of 3-11 kW is most probably less than 2 %.

 

[MartinLe]

An added complexity: the motors are specified as EEx II ... whatnot.

finally got hold of a likely supplier, they where pretty unenthusiastic bc. of added price.

 

[ScottyUK]

If the intention is to write a specification which effectively excludes certain manufacturers from the tender process then it likely makes sense. Sometimes that is necessary to remove the bottom-feeders. If you take this tactic too far then your commercial people will likely object if there is only one compliant bidder. Equally you may use the situation where a bidder offers an IE3 motor instead of IE4 as a commercial lever to negotiate price.

 

[MartinLe]

The intention of the customer is to save power. there are indeed only ~2% difference in efficiency between IE3 and IE4.
After some more digging it turns out that ABB and Siemens don't deliver IE4 motors in this size with the ex protection required (far larger size would be different).
Just like micalbranch said.