Service Life Expectancy Of Cj1W-Oc201/211 Relays; Contact Current Vs. Service Life Characteristic; Inductive Load; A-1-3 Precautions On Contact Output Units - Omron CJ2 CPU UNIT User Manual

A-1-3 Precautions on Contact Output Units

Service Life Expectancy of CJ1W-OC201/211 Relays

The service life expectancy of the relays (NY-24W-K-IE) in the CJ1W-OC201/211 Contact Output
Units is shown in the following diagrams. Use the diagrams to calculate the relay service life based
on the operating conditions, and replace the relay before the end of its service life.

Contact Current vs. Service Life Characteristic

Service Life with AC Load
300
200
100
50
30
240 VAC cos φ = 0.4
20
10
5
3
2
0.1 0.2 0.3
Precautions for Correct Use Precautions for Correct Use
The diagrams show the life expectancy of the relay itself. Do not use a contact current, therefore,
that exceeds the maximum switching capacity specified in the specifications for each Contact
Output Unit. If a switching capacity exceeding the specifications is used, the reliability and life
expectancy of other parts will be reduced and the Unit may malfunction.

Inductive Load

The life of the Relay varies with the load inductance. If any inductive load is connected to the Con-
tact Output Unit, use an arc killer with the Contact Output Unit using an inductive load. (See next
page.)
Be sure to connect a diode in parallel with every DC inductive load that is connected to the Contact
Output Unit.
Contact Protection Circuit
Arc killers are used with the Contact Output Unit in order to prolong the life of each Relay mounted
to the Contact Output Unit, prevent noise, and reduce the generation of carbide and nitrate deposits.
However, if arc killers are used incorrectly, they can reduce relay life. Using an arc killer can also
cause a delay in the resetting time (shut-off time). Arc killer circuit examples are listed in the follow-
ing table.
CJ2 CPU Unit Hardware User's Manual
120 VAC, resistive load
240 VAC, resistive load
120 VAC cos f = 0.4
0.5 0.7 1 2 3 5
Contact current (A)
Service Life with DC Load
300 24 VDC τ = 7 ms
200
100
50
30
20
10
5
3
2
0.05 0.1 0.2 0.3 0.5 0.7 1
Contact current (A)
Switching frequency: 1,800 operations/hour max.
Appendices
24 VDC, resistive load
2 3 5
A-57