Operating instructions

Operation with only one supply frequency inverter

MICROMASTER 420 / 440 – DC link coupling between several

Frequency inverters

A&D SD Page 19/32

4.8 Operation of the fans in the frequency inverters

In order that the supply inverter is not thermally overloaded, when one of

the connected frequency inverters receives an ON command then the

supply inverter must also receive an ON command. This therefore

guarantees that its fan is operational and the cooling is adequate. If the

supply inverter is powered-up as a result of the internal fan, but the

connected motor may not rotate, then the setpoint can be inhibited in front

of the ramp-function generator for both MICROMASTER420 and

MICROMASTER440 using parameter P1142. This guarantees that the

motor does not rotate even if a setpoint is present.

Exception:

If an option is inserted at the BOP link interface at the supply inverter (e.g.

Profibus module, encoder module, etc.) then for frequency inverter sizes A,

B, and C, the fan is always operational when the line supply voltage is

connected and an ON command to power-up the fan is not necessary.

4.9 Risk for the connected frequency inverters in the case of a DC

link short-circuit

When a short-circuit or ground fault occurs in the DC link (in the DC link

coupling or within a frequency inverter), there is a risk that all of the

frequency inverters, connected to the DC link, will be destroyed. This is the

reason that when the drive system is engineered, this aspect should be

carefully taken into account. The number of frequency inverters within a DC

link group should be kept as low as possible.

4.10 Operation on IT line supplies

The frequency inverter without integrated EMC filter can also be used in a

DC link group connected to an IT line supply. In this case the Y capacitor of

the frequency inverter should be removed. A description is provided in the

Operating Instructions of the frequency inverter.