MIL-DTL-17587C(SH)
3.4.16.2.2 Solid-state overcurrent trip device. Solid-state overcurrent trip devices shall have provisions for
determining that the device is functioning and that no parts have failed. The device shall have a provision through
a test socket for secondary injection testing to check the overload calibrations.
3.4.16.2.2.1 Long-time delay trip element.
3.4.16.2.2.1.1 Long-time delay pickup settings. Available long-time delay pickup settings for each trip coil or
sensor rating shall be in accordance with the applicable specification sheet. The settings shall be adjustable and
clearly marked on the trip unit. Unless otherwise specified in the applicable specification sheets or noted in the
qualification package, a pickup setting shall be provided that equals 1.5 times the continuous current setting
established by the coil or sensor rating. The maximum error for any setting shall not exceed ±10 percent.
3.4.16.2.2.1.2 Long-time delay band settings. Available long-time delay band settings shall be in accordance
with the applicable specification sheet. The operating characteristics of each band setting shall be in accordance
with the applicable specification sheet. The settings shall be adjustable and clearly marked on the trip unit. The
operating characteristics shall apply for single-pole operation, for any two poles in series, for three poles in series,
and for three-phase operation.
3.4.16.2.2.2 Short-time delay trip element.
3.4.16.2.2.2.1 Short-time delay pickup settings. Available short-time delay pickup current settings shall be in
accordance with the applicable specification sheet. The settings shall be adjustable and clearly marked on the trip
unit. Unless otherwise specified in the applicable specification sheet, the maximum error for any setting shall not
exceed ±10 percent.
3.4.16.2.2.2.2 Short-time delay band settings. Available short-time delay band settings shall be in accordance
with the applicable specification sheet. The settings shall be adjustable and clearly marked on the trip unit. The
characteristics apply for single-pole operation, for any two poles in series, for three poles in series, and for single-
phase and three-phase operation. Values of operating time and resettable delay shall not fall outside the
predetermined short-time delay band.
3.4.16.2.2.3 Instantaneous trip element. The instantaneous trip element shall trip the circuit breaker with no
intentional time delay other than filtering that may be required to eliminate nuisance tripping. Instantaneous
pickup settings shall be adjustable and clearly marked on the trip unit. The pickup current value setting shall be
accurate to within ±10 percent for settings up to 10 times the trip coil rating and ±20 percent for settings above 10
times the coil rating. The instantaneous trip feature may have a setting to turn it off. The characteristics of
instantaneous trip apply for single-phase and three-phase operation.
3.4.17 Attachments. Attachments shall include the electric closing device, undervoltage release device (see
6.3.30), undervoltage lockout device, shunt trip, auxiliary switch, secondary disconnect device, hold-closed
mechanism, operations counter, mechanical position indicator, indicator light, trip on power up (TOPU) device,
position indicator for rack-in/rack-out, and cell switch.
3.4.17.1 Temperature rise. Temperature rise of electric closing devices, undervoltage release devices, shunt
trips, auxiliary switches, and secondary disconnect devices shall not exceed the requirements of molding and
insulating materials specified in MIL-E-917 in as-new condition. As circuit breakers and attachments are cycled
and tested for qualification, temperature rise limits may vary. See 4.5.9.3 and Table V for these test requirements.
3.4.17.2 Endurance. Electric operating mechanisms, undervoltage release devices, and shunt trips shall have
the ability to be cycled continuously for the number of electrical endurance operations specified herein. Rate of
operations shall be as specified for the circuit breaker electrical endurance test in the applicable specification sheet.
3.4.17.3 Electric closing devices. Electric closing devices shall have the following characteristics:
a. Closing devices may be a motor, solenoid, or stored energy system, which consists of a closing spring (see
6.3.5) or springs charged by an electric motor with an electrical or mechanical closing release (see 6.3.4).
b. The nominal control voltage and their ranges, when measured at the terminals of the operating motors or
solenoids with full operating current, shall be as specified in Table II. The closing springs shall be recharged
immediately after the circuit breaker closes.
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