MCD 200 Series
MG.17.D3.02 – VLT is a registered Danfoss trademark
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Output Relay Compatibility
Overview
The MCD 201 soft starter has one fixed (Main
Contactor) output relay.
The MCD 202 soft starter has one fixed (Main
contactor) and one programmable (Trip/Run) output
relay.
These PCB mount relays are often used for line
contactor control.
Recent advances in contactor design have lead to
many manufacturers using electronic contactor coils.
Initially these coils may appear to meet the
specifications of the PCB mount relays. However, in
some instances these electronic contactor coils have a
high initial inrush current due to the internal switch
mode power supply circuitry. This can have a
damaging effect on the PCB mount relays if the
contactor coil is switched directly.
Solution
Before using an MCD 200 soft starter PCB mount
output relay for direct switching of an electronic
contactor coil, consult the contactor
manufacturer/supplier to see if this is advisable.
Certain contactor manufacturers (eg Klockner-Moeller)
state that you cannot use PCB mount relays for direct
switching of their electronic contactor coils.
If this is the case, there are two solutions:
1. Use a MCD 200 soft starter output relay to control
a slave relay. This slave relay can then be used to
directly switch the electronic contactor coil circuit.
2. Some contactor brands have a volt free electronic
input (low voltage/low current). If this is available,
the MCD 200 output relay can be wired directly
into this input for contactor control.
