MI 3101 EurotestAT: Appendix E
Reduced low voltage supply systems
110
E Appendix E - Reduced low voltage supply
systems
E.1 Standard reference
BS7671
E.2 Fundamentals
Special supply systems are applied where inherent protection to electric shock is required
but no SELV used. Reduced low voltage supply with ground reference can be used for this
purpose.
There are two options with 110 V nominal voltage.
55 V
55 V
PE
L1
L2
110 V
63 V
63 V
L1
L2
110 V
63 V
L3
110 V
110 V
Single phase with center tap connected
to PE (i.e. 2 x 55 V).
No neutral line.
Three phase star connection, center tap
connected to PE (i.e. 3 x 63 V).
No neutral line.
Figure E.1: General reduced low voltage supply systems
E.3 MI 3101 guides
The user has to select the reduced low voltage supply system in the instrument before
testing it. The procedure for selecting the reduced low voltage supply system is defined in
chapter
4.4.2 Supply system, Isc factor, RCD standard.
Once the reduced low voltage
system is selected the instrument can be used immediately. The instrument keeps
selected reduced low voltage system when it is turned off.
When the instrument detects appropriate voltage levels for selected reduced low voltage
system, the terminal voltage monitor shows reduced low voltage system icon RV.
