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A-2-3
Precautions on Contact Output Units
Service Life Expectancy
The service life expectancy of the relays (NY-24W-K-IE) in the CJ1W-OC201/211 Contact Output
Units depends on the type of load, the contact current, and the ambient temperature. Use the follow-
ing 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 above charts show the life characteristics for the individual relays. Do not exceed the speci-
fications of the Relay Output Units. 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. (See next page.)
Be sure to connect a diode in parallel with every DC inductive load that is connected to the Contact
Output Unit. The usage of an arc killer has a significant effect on the service life of the contacts.
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.
NJ-series CPU Unit Hardware User's Manual (W500)
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
24 VDC τ = 7 ms
300
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-53
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