Operating instructions

Operation with up to three supply inverters

MICROMASTER 420 / 440 – DC link coupling between several

Frequency inverters

A&D SD Page 31/32

5.6 DC link voltage controller operation

For a DC link coupling, the V

DCmax

controller, integrated in the

MICROMASTER 420 and MICROMASTER 440 frequency inverters may

not be used. This controller is activated in the factory setting which means

that it must be disabled by setting parameter P1240 to 0.

However, the kinetic buffering in the MICROMASTER 440 frequency

inverter can be used to buffer the DC link during brief power failures. In this

case, parameter P1240 must be set to 2.

5.7 Accommodating the frequency inverters connected to the DC

link in a cabinet

The supply inverters must be located next to one another in the electric

cabinet in the same sequence as their rated powers. Next to the supply

inverters, the inverters connected to the DC link must also be located next

to one another in the same sequence as their rated powers. The DC link

couplings should be as short as possible.

5.8 Operation of the fans in the frequency inverters

In order that the supply inverters are not thermally overloaded, when one of

the connected frequency inverters receives an ON command then all of the

supply inverters must also receive an ON command. This guarantees that

their fans are operational and the cooling is adequate. If the supply

inverters are 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 inverters (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.