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Page Title:
Specified pickup, hold, and dropout values |
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|  MIL-R-5757H
e. Number of activations prior to measurement: None.
f. Number of test activations: Three.
g. Number of measurements per activation: One in each closed contact position.
4.6.8.2 Specified pickup, hold, and dropout values (voltages) (or current) (see 3.10.2). Specified
pickup, hold, and dropout values (voltage) shall be measured as specified in 4.6.8.2.1, 4.6.8.2.2, or
4.6.8.2.3. For qualification inspection, the relay shall be mounted in each of three mutually
perpendicular planes, unless otherwise specified (see 3.1). For quality conformance inspection,
mounting position is optional. A suitable indicating device shall be used to monitor contact position.
During the test, all contacts shall not change state (break or remake) when the coil is energized at or
above the specified pickup value (voltage); when the coil voltage (or current) is lowered to any value at
or above specified hold value (voltage); or when the coil voltage (or current) is reduced from the
specified dropout value (voltage) to zero. It is permissible to perform specified pickup, hold, and dropout
values (voltages) using step function voltage changes as specified in 4.6.8.2.1, 4.6.8.2.2, and 4.6.8.2.3.
Due to the fact that slow ramping will overheat relay coils and vary specified pickup, hold, and dropout
values (voltages), the step function method shall be the governing method in cases of dispute.
4.6.8.2.1 Specified pickup value (voltage). The voltage shall be increased from zero until the relay
operates, and the specified pickup value (voltage) shall be measured. It is permissible to perform
specified pickup value (voltage) using a step function voltage change as follows and as illustrated on
figure 5.
a. Step up to the maximum specified pickup value (voltage), contacts should have transferred and
all normally-open contacts should be made.
b. Increase to rated coil voltage (or current).
c. Step down to specified hold value (voltage). Normally-open contacts must still be making.
d. Step down to specified dropout value (voltage), all contacts should have transferred and all
normally-closed contacts should be making.
e. Step down to zero voltage.
4.6.8.2.2 Specified hold value (voltage). Rated voltage (or current) shall be applied to the coil. The
voltage shall then be reduced to the specified hold value (voltage) (see 3.1 and 6.8). All contacts shall
not change state. It is permissible to perform this test using the step function voltage program described
in 4.6.8.2.1 and figure 5.
4.6.8.2.3 Specified dropout value (voltage). Rated voltage (or current) shall be applied to the coil.
The voltage shall then be gradually reduced until all contacts return to the de-energized position and the
specified dropout value (voltage) shall be measured. It is permissible to perform this test using the step
function voltage program described in 4.6.8.2.1 and figure 5.
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