Electrical Codes, Standards, Recommended Practices and Regulations

Overload relays also have a limit of self-protection which is defined for device operation at

40

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C. NEMA ICS 2 defines it as:

The maximum current value that an overload relay can respond to without sustaining damage

that will impair its function. [25]

Inverse-time overload relays also have time-current characteristic curves for operation at

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C ambient conditions. Those curves express:

the maximum operating times in seconds under the designated conditions associated with the

current rating, at current values corresponding to multiples of the current rating. [26]

Overload relays have contacts which are controlled by the relay operation. Those contacts ...