MIL-STD-1275E
3.6.4 Intermittent contact.
Intermittent contact occurs when electrical contacts in a switch or relay change state. A common way of describing intermittent contacts is the use of the terms "contact bounce" or "chattering relay." Mechanical vibration may also affect the operation of mechanical contacts and cause this to occur. The settling period and pulse widths associated may vary depending on the
construction of the contacts. Figure 5 shows an example of an intermittent contact waveform.
Volt
VNOM
0
Time
Figure 5. Sample intermittent contact waveform.
Intermittent contact may affect operation of equipment in one of two ways. First, equipment power feed(s) controlled by the relay/switch may be directly affected with resets, dropouts, etc. Second, the electrical noise generated by the intermittent contact on a directly connected wire may be coupled to nearby wires in the wiring harness through electric/magnetic field coupling.
3.7 Reverse polarity.
Reverse polarity is defined as the inverted connection of the EUT's power terminal(s) to the vehicle's power system. The positive (+) terminal of the EUT is connected to the negative (-) or "ground" terminal of the vehicle's power supply system. The negative (-) terminal of the EUT is connected to the positive (+) terminal of the vehicle's power supply system.
4 GENERAL REQUIREMENTS
4.1 Reverse polarity.
Utilization equipment shall protect itself against damage due to input power with reverse polarity. With reverse polarity voltage applied to the input power terminals of the utilization equipment, the magnitude of the reverse polarity input current shall be equal to or less than the magnitude of the utilization equipment normal operating current.
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