Vacon NX User Manual page 165

ACTIVE FRONT END (NXA) vacon • 163
The Active Front End unit must not be connected to mains without pre-charging. In order to ensure
the correct operation of the pre-charging circuit, the input circuit-breaker or contactor, as well as
the pre-charging circuit contactor, must be controlled by the Active Front End unit. The input
circuit-breaker or contactor as well as the pre-charging circuit contactor must be connected as
shown in Figure 94.
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Figure 94. Wiring diagram for AFE unit
The example shown in Figure 94 uses a spring-return switch. The switch has positions 0-1-START.
The spring returns the switch from position START to position 1. To start the pre-charging, the
switch is turned from position 0 via 1 to START. When pre-charging starts, the switch can be
released and it returns to position 1. No other control measures are required. The Active Front End
application controls the main contactor of the system with Relay Output RO2, see Figure 95. When
pre-charging of the intermediate circuit is ready the main contactor will be closed. The status of the
main contactor is monitored via digital input (Default is DIN4). As a default the main contactor
monitoring is ON but it can be set OFF with parameter. The main contactor should not be possible
close without pre-charging.
To open the main contactor, simply turn the switch to 0. The contactor should not be opened under
load. Opening the contactor under load will shorten its service life.
NOTE! Wirings what are used for connecting the pre-charging circuit to the intermediate circuit has
to be double insulated.
NOTE! Enough space must be reserved around the resistors to ensure sufficient cooling. Don't
place any heat sensitive components near the resistors.
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com
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