Delta IED-S Series User Manual page 16

Asymmetric Ground System (Corner Grounded TN Systems)
Caution: Do not remove the RFI switch while power to the motor drive input terminal is ON.
In the following four situations, you must remove the RFI switch. This is to prevent the system from
grounding through the RFI capacitor and damaging the motor drive.
1. Grounding at a corner in a triangle configuration
3. Grounding at one end in a single-phase
configuration
In the situation as the diagram on the right shows, you can
use the RFI switch to pass through RFI capacitor to make
an internal grounding and reduce electromagnetic radiation.
In a situation with higher requirements for electromagnetic
compatibility and a symmetrical grounding power system,
you can install an EMC filter. For example, the diagram on
the right is a symmetrical grounding power system.
Conditions for removing the RFI switch
2. Grounding at a midpoint in a polygonal
L 1
L 2
L 3
4. No stable neutral grounding in a three-phase
L 1
N
Using the RFI switch
1-9
configuration
autotransformer configuration
L 1
L 2
L 3
Chapter 1 Introduction | IED-S
L 1
L 2
L 3
L 1
L 2
L 3
L 1
L 2
L 3