4.2 Wiring the Power Supply
4.2.1 Common Precautions
■
To avoid the influence of noises
● Use a low noise power supply.
● The inherent noise resistance is sufficient for the noise superimposed on the power wires,
however, the noise can be attenuated further by using the isolation transformer.
● Also, twist the power supply cables to minimize adverse effects from noise.
■
Keep the power supply wiring separate
Wiring to the CPU unit, input devices, and power equipment should have separate wiring
systems.
■
Measures regarding power supply sequence (start up sequence)
● Have the power supply sequence such that the power supply of PLC turns off before the
power supply for input and output.
● If the input/output power supplies are turned off before the power PLC, the CPU unit will
detect the input fluctuations and may begin an unscheduled operation.
4.2.2 Wiring for Power Supply Units
■
Terminal layout for power supply units
WUME-FP7CPUH-09
4.2 Wiring the Power Supply
4-9