Abstract: The present invention relates to improvements to automatic permanently installed insulation resistance test equipment. More particularly, the present invention relates to improvements to insulation test equipment for testing low voltage, medium voltage, and high voltage electrical equipment on the order of the rated voltage level while limiting the maximum output current to a safe level. The preferred test output voltage of the insulation test equipment would have a maximum test output of 5000 VDC, due to design considerations, but the AIRT test output could be made to be higher, up to a maximum of 15,000 VDC. After installation of the insulation test equipment in the control cabinet of the electrical equipment there will be no requirement to open the control cabinet to operate the insulation test equipment. The improvements will also allow personnel to perform an insulation test on electrical equipment without having to manually isolate the electrical equipment from the power source to perform the testing.

Abstract: The present invention relates to improvements to automatic permanently installed insulation resistance test equipment. More particularly, the present invention relates to improvements to insulation test equipment for testing low voltage, medium voltage, and high voltage electrical equipment on the order of the rated voltage level while limiting the maximum output current to a safe level. The preferred test output voltage of the insulation test equipment would have a maximum test output of 5000 VDC, due to design considerations, but the AIRT test output could be made to be higher, up to a maximum of 15,000 VDC. After installation of the insulation test equipment in the control cabinet of the electrical equipment there will be no requirement to open the control cabinet to operate the insulation test equipment. The improvements will also allow personnel to perform an insulation test on electrical equipment without having to manually isolate the electrical equipment from the power source to perform the testing.

Abstract: The present invention relates to improvements to automatic permanently installed insulation resistance test equipment. More particularly, the present invention relates to improvements to insulation test equipment for testing low voltage, medium voltage, and high voltage electrical equipment on the order of the rated voltage level while limiting the maximum output current to a safe level. The preferred test output voltage of the insulation test equipment would have a maximum test output of 5000 VDC, due to design considerations, but the AIRT test output could be made to be higher, up to a maximum of 15,000 VDC. After installation of the insulation test equipment in the control cabinet of the electrical equipment there will be no requirement to open the control cabinet to operate the insulation test equipment. The improvements will also allow personnel to perform an insulation test on electrical equipment without having to manually isolate the electrical equipment from the power source to perform the testing.

Abstract: A minimum off-time device according to the present invention that delays the restart of a compressor motor of a refrigeration system after power provided to the motor has been interrupted. The minimum off-time device is a standalone unit that is located outside the refrigeration system. The device is retrofitted to the refrigeration system by simply plugging the power line of the system into the device, which is then plugged into an AC wall receptacle, or alternatively, the device can be connected between the power line of the refrigeration system and an electrical circuit breaker panel. The minimum off-time device normally allows power from the AC power source to reach the refrigeration system. However, when a power interruption occurs at the AC power source, and subsequently, power is reapplied, the minimum off-time delay device immediately disconnects the refrigeration system from the AC power source and begins a timing sequence.

Abstract: Insulation test equipment for testing high voltage electrical equipment at rated voltage levels up to above 5 kV. A multistage rectifier-capacitor voltage multiplier ladder is used to boost the test voltage to the desired level, while keeping the current and load capacity to a safe, low level. If an appreciable amount of current is attempted to be drawn, such as might occur with accidental human contact, the rectifier--capacitor ladder breaks down to limit the voltage and current to safe levels. Two separate current limit resistors are provided for both outgoing and incoming voltages of the test equipment. One is installed in the test apparatus and the other is installed on the high voltage fuse at the contact point between the motor windings and the test lead. The voltages and insulation current generated by the test equipment are monitored indirectly through opto-coupler circuits to isolate and protect the monitoring circuits and the operator.

Abstract: An automatic insulation tester tests the insulation resistance of electrical equipment when the electrical equipment is inoperative. The automatic insulation tester is automatically rendered operative when the electrical equipment is inoperative, and is automatically rendered inoperative when the electrical equipment is operative. The automatic insulation tester applies a voltage on the order of the rated voltage of the electrical equipment to the electrical equipment and measures and displays the insulation resistance of the electrical equipment. When the insulation resistance falls below a predetermined value, an indicator is activated, and remains in an activated state until the insulation resistance of the electrical equipment rises above the predetermined value and the automatic insulation tester is manually reset.

Abstract: An automatic insulation tester tests the insulation resistance of electrical equipment when the electrical equipment is inoperative. The automatic insulation tester is automatically rendered operative when the electrical equipment is inoperative, and is automatically rendered inoperative when the electrical equipment is operative. The automatic insulation tester applies a voltage on the order of the rated voltage of the electrical equipment to the electrical equipment and measures and displays the insulation resistance of the electrical equipment. When the insulation resistance falls below a predetermined value, an indicator is activated, and remains in an activated state until the insulation resistance of the electrical equipment rises above the predetermined value and the automatic insulation tester is manually reset.