Operating instructions

Operation with only one supply frequency inverter

MICROMASTER 420 / 440 – DC link coupling between several

Frequency inverters

Example 2:

3-ph. 380-480V AC 50/60Hz

Line fuses

3 x 10A

Line

contactor

Line reactor

Inverter

3 ~

Motor

3 ~

Motor Motor

MM440

1,5kW

MM440

0,55kW

MM420

0,55kW

PE PE PE

PEPEPE

Fig. 2-3: DC link coupling of a 1.5kW MM440 frequency inverter with an

0.55kW MM440 and a 0.55kW MM420

In this particular case, the DC link does not have to be fused, because:

o All of the frequency inverters require line fuses of 3x10A and these are

used at the input of the supply inverter.

o The total DC link current (summed) of the two connected frequency

inverters each with 0.55kW is, according to Table 2-2 I

DCtot

= 2*2A = 4A.

For this current, a cross-section of 1.5mm² (routing type B2, 2

conductors conducting current, 40°C ambient temperature) can be used

which are adequately protected using the 3x10A line fuses.

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