Abstract: A “motorless” power electronic test device for testing adjustable speed motor drives without having to connect motors to the drive includes a bidirectional internal power converter, filtering, a charging switch for charging the capacitors of internal and external power converters, line switches for setting the test mode and operating the device, and a switch controller. The test device can be set to separately test an external power converter or an external rectifier, with the internal power converter operating in an AC-to-DC mode for testing the external power converter, and operating in a DC-to-AC mode for testing the external rectifier. The motorless test device recycles test power to reduce testing losses and carbon footprint. It is also much lighter and more convenient to handle than a full-load motor-absorber and, therefore, more amenable to deployment as a portable unit that can be readily transported to customer sites.

Abstract: A transformer economizer automatically disconnects a main electric power transformer from a grid power line during low-load periods, and automatically reconnects the main transformer to the grid power line during high-load periods, to reduce low-power electricity losses incurred by the main transformer. The main transformer is therefore deenergized and a much smaller auxiliary transformer is energized during low-load periods to reduce the low-power electricity losses incurred by the main transformer. The main transformer is then automatically switched back into service during high-load periods, while the auxiliary transformer is switched out of service. This provides long-term energy, cost, and carbon footprint savings by automatically switching the large transformer's loads to a much smaller auxiliary transformer, and therefore proportionally lower losses, during light-load conditions.

Abstract: A transformer economizer automatically disconnects a main electric power transformer from a grid power line during low-load periods, and automatically reconnects the main transformer to the grid power line during high-load periods, to reduce low-power electricity losses incurred by the main transformer. The main transformer is therefore deenergized and a much smaller auxiliary transformer is energized during low-load periods to reduce the low-power electricity losses incurred by the main transformer. The main transformer is then automatically switched back into service during high-load periods, while the auxiliary transformer is switched out of service. This provides long-term energy, cost, and carbon footprint savings by automatically switching the large transformer's loads to a much smaller auxiliary transformer, and therefore proportionally lower losses, during light-load conditions.

Abstract: A “motorless” power electronic test device for testing adjustable speed motor drives without having to connect motors to the drive includes a bidirectional internal power converter, filtering, a charging switch for charging the capacitors of internal and external power converters, line switches for setting the test mode and operating the device, and a switch controller. The test device can be set to separately test an external power converter or an external rectifier, with the internal power converter operating in an AC-to-DC mode for testing the external power converter, and operating in a DC-to-AC mode for testing the external rectifier. The motorless test device recycles test power to reduce testing losses and carbon footprint. It is also much lighter and more convenient to handle than a full-load motor-absorber and, therefore, more amenable to deployment as a portable unit that can be readily transported to customer sites.