Common Items

NEC Electronics' photocoupler and optical MOS FET products meet many overseas safety standards, but why is this necessary?

There are regulations applying to the isolation of the primary circuit and secondary circuit in sets incorporating photocouplers (power supplies, FA devices, etc.). The photocoupler accomplishes this isolation function. Therefore, if the photocouplers meet these regulations, the sets themselves may be exempted from the relevant qualification tests. This is why NEC Electronics has developed photocouplers to meet these overseas safety regulations.

The status of each of NEC Electronics' photocoupler and optical MOS FET product in terms of meeting overseas safety regulations can be checked at the following URLs.
[Photocouplers]
   http://www.ncsd.necel.com/opto/english/safety.html
[Optical MOS FETs]
   http://www.ncsd.necel.com/opto/english/safetyocmos.html

(2007/11)

What are the meanings of the terms isolation voltage, creepage distance, isolation thickness, and clearance?

These terms are defined as follows.

- Isolation voltage
It indicates the maximum value of the AC voltage that can be applied between the input pin and the output pin, expressed as a root mean square (r.m.s) value.
The measurement conditions are normally Ta = 25°C, RH = 60%, with application of the rated AC voltage between all input-side pins and all output-side pins for 1 minute.

- Creepage distance
It indicates the minimum distance between the two conductors (input pin, output pin) along the insulating material.

- Isolation thickness
It indicates the minimum thickness of the insulating material between the two conductors (input, output).

- Clearance
It indicates the minimum distance between the two conductors (input pin, output pin) in the atmosphere.

For details about the above three terms, go to the following URL.

http://www.ncsd.necel.com/opto/english/parameter_p/index.html

(2007/10)