Mains contactors of 938X vector with two power stages connected in parallel

Question:

Mains contactor - How can the connection of the EVF938xEV be practised?

Answer:

The vector devices of high performance (9381EV...9383EV) have a parallel connection with two units (master and slave).

Usually for master and slave separate mains contactors are used (see figure). Both mains contactors are supposed to be triggered in order to synchronize the charging process of both units and to avoid negative effects on the mains inputs of the devices (charging resistor and rectifier). In spite of simultaneous drive the remaining differences of the switching instants in the millisecond-field are negligible due to component tolerances of the mains contractors.

Remarks to the below figure:

• *) = Master and slave are supposed to be connected via 2 connecting bars for +Ug and -Ug
• Between master and slave the control cables intended in the device are to be connected.
• The shown motor connection is valid for a resulting motor cable length ≥ 10 m
• Further information can be taken from the operating instruction, chapters 'Electrical Installation - Types 9381-9383 Master and Slave' and 'Motor connection'