Method 4.7.29 is a low temperature operation test for military relays. The relay is subjected to the specified low temperature for a period of 48 hours. At the end of this period, with the relay still at the low temperature, the pickup voltage, dropout voltage, and contact voltage drop are measured.
The measurements are performed as specified in the standard electrical test methods, except that a 30-minute pre-conditioning period is not required. These tests are accomplished in the sequence listed and in a minimum amount of time to prevent significant temperature change.
This test evaluates the relay’s ability to function properly in extreme cold conditions encountered in military operations.