Wiring For The Power Supply; Figure 4-2 An Example Of Power Supply Wiring With An - Hitachi HSC-2100 Hardware Manual

4.2 Wiring for the Power Supply

The wiring for the power supply to I/O units must be insulated from the control power source by
using an electrostatic shielded isolation transformer. Shown below is wiring diagrams of two
different power supply installations, one in which an isolation transformer is mounted in the
power distribution panel, and one in which an isolation transformer is mounted in the
programmable controller cubicle.
Case 1 -- an isolation transformer is mounted in the power distribution panel:
Power distribution panel
Power supply:
100 to 120 VAC,
single phase, 50/60 Hz
Symbols: NFB, non-fuse breaker; TB, terminal block.

Figure 4-2 An Example of Power Supply Wiring with an

Isolation
NFB
transformer
TB
(collecting
Panel ground
LG wires)
(connected to
cubicle)
Cubicle ground
Class D grounding
Isolation Transformer Mounted in the Power Distribution Panel
Programmable controller cubicle
NFB
TB
(collecting
LG wires)
Cubicle ground
Class D grounding
4-3
4 WIRING
H
LPU unit or
CPU unit
N
LG FG
H
I/O unit
N
LG FG
Grounding metal
piece (insulated
from cubicle)
Class D grounding
TB
(collecting
FG wires)