Abstract: An automotive battery charger or other electrical device which draws substantial amounts of power is provided with a variable delay mechanism which prevents turn on of the device when power is applied. The duration of the delay is determined by a random or pseudorandom number generator, so that a plurality of different electrical devices will, in effect, be turned on at random times following application of power. The maximum turn on delay could be conveniently limited to a specific period of time, so that critical operating times of the device, such as the charging cycle of a battery charger, are not shortened excessively.

Abstract: A personnel protection system for electrical connections is disclosed, which is of the type that differentially senses the current flow between the power lead and the return lead (or between two power loads) is provided with an unbalancing impedance which makes the current difference between the two leads sufficiently high to trip the device and cause the power to be disconnected. A utilization device is similarly provided with an imbalanced impedance. However, that impedance is calculated to counteract the current imbalance caused by the first impedance, so that when the cable is connected to the utilization device, the current balance between the two conductors is restored, and power connection is maintained in the cable. Thus, the system does not provide continuous power unless predetermined conditions considered safe for securing the power are fully satisfied.

Abstract: A personnel protection system for electrical connections is disclosed, which is of the type that differentially senses the current flow between the power lead and the return lead (or between two power loads) is provided with an unbalancing impedance which makes the current difference between the two leads sufficiently high to trip the device and cause the power to be disconnected. A utilization device is similarly provided with an imbalanced impedance. However, that impedance is calculated to counteract the current imbalance caused by the first impedance, so that when the cable is connected to the utilization device, the current balance between the two conductors is restored, and power connection is maintained in the cable. In addition, the current flow in the second impedance is sensed and, if it is not at the correct level, electrical power to the load is disconnected in the same manner as when an imbalance occurs.