Yaskawa 120 Series I/O Modules - Manual (Page 279)

6 Installation and Wiring
6.4.9 External Power Supplies
6-52
6.4.9 External Power Supplies
1) A standard DC stabilized power supply should be used as an external power supply for
DC I/O Modules.
2) Add a noise filter on the AC input side of the DC stabilized power supply, for special
modules such as Analog Modules or Counter Modules to prevent the introduction of
noise. Do not run the primary and secondary side of the noise filter and the DC output
through the same wiring duct.
3) If a simple DC power supply such as a full-wave rectifying power supply must be used,
minimuze ripple by adding a smoothing capactor, and observe the following precautions.
• Instantaneous output voltage including ripple voltage should always be within
the maximum allowable voltage range of the DC I/O Modules.
• Output voltage, even when power is turned ON and OFF, should never exceed
the maximum allowable voltage of the DC I/O Modules.
• Prevent the introduction of surge voltage by adding a noise filter on the input to
the rectifying device.
• Prevent surge voltage that may occur when a contactor is installed at the full-
wave rectifying output by applying a surege suppressor or other device between
contactor outputs at the Module.