Relay Life and Preventive Maintenance
The DAQ970A Relay Maintenance System automatically counts the cycles on each relay in the instrument
and stores the total count in nonvolatile memory on each switch module. Use this feature to track relay fail-
ures and predict system maintenance requirements.
Relays are electromechanical devices which are subject to wear-out failure modes. The life of a relay, or the
number of actual operations before failure, is dependent upon how it is used – applied load, switching fre-
quency, and environment.
You can use the graphs shown in this section to estimate relay lifetimes for your application. Additional
background information is also provided to give you a better understanding of relay wear-out mechanisms.
In general, relay lifetimes depend heavily upon the signals that are being switched and the types of meas-
urements being performed.
l Switching typical signal levels will result in relay lifetimes from 1,000,000 to 10,000,000 oper-
ations.
l High-power switching (>25% rating) or high-voltage switching (>100 V) applications will yield
relay lifetimes from 100,000 to 1,000,000 operations.
l Low-voltage switching (<25% rating) and low-current switching (<10 mA) applications will
yield relay lifetimes to 10,000,000 operations.
l RF switching applications seldom exhibit relay lifetimes exceeding 1,000,000 operations due
to more stringent constant resistance requirements (typically less than 0.2 Ω).
Keysight DAQ970A User's Guide 229
4Measurement Tutorials
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