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Frequently Asked Questions

What does normally open, normally closed mean?

Why use a relay vs a circuit breaker or switch?

When a relay has demonstrated a given failure rate, is the failure rate applicable for all rated load conditions?

How does a relay work?

What is the difference between 50, 60, and 400 HZ?

Is MCBF a guaranteed period of failure-free service?

Why is relay reliability expressed in MCBF rather than MTBF like other electronic components?

What does “Hi-Rel Relay” really mean?

Why can’t a power contactor switch low current?

Why do we have 3-phase ratings available?

What is the difference between resistive, inductive, motor, and lamp loads?

What is a latch relay, and where is it used?

Explain center-off relays. When and where should they be used?

Can a 99% reliability for a particular mission time be achieved when a relay is only capable of 90%?

Are there any latent costs that should be considered in the procurement of relays?

Would a demonstrated failure rate of 0.001% per 10,000 operations (one failure per billion operations) at the 90% confidence level be a reasonable failure rate to expect from a Hi-Rel relay?

Is there more than one method used to calculate relay reliability failure rates?

Do initial screening tests have any effect on the reliability of relays during the use life?

What is the effect on reliability by using relays in series to reduce high current arcs?

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