A meter for measuring electric power consumed by a plurality of branch circuits includes interchangeable current transformers including respective transformer memories for storage of transformer characterization data and enables self-discovery of a phase shift induced by respective current transformers and the phase of current conducted by each branch circuit.

Branch current monitor with calibration

A current switch is automatically calibrated when a flow of electric current is initiated in a power cable.

Current switch with automatic calibration

The size of a status indicator for monitoring a current in a power cable is reduced by integrating a bobbin for the secondary winding with a current transformer core and integrating a circuit board including output terminals with a current transformer assembly.

Split core status indicator

In a digital branch circuit monitor, compensation for the phase error is accomplished by selecting a voltage sampled at a time temporally offset from the sampling time of the current by an interval quantifying the phase shift of the secondary current relative to the primary current that is characteristic of a current transformer.

Branch circuit monitor power measurement

A power meter for monitoring current in a power cable annunciates an alarm if the current transgresses one or more alarm current limits. False alarms are avoided by delaying the activation of the alarm for a delay interval following determination that current is flowing in the monitored conductor.

Branch current monitor with an alarm

Electronic trip relay

PURPOSE:To obtain a motor operation circuit which is free from the influence of the vibration of a load driven by the motor and improves the lifetime of circuit parts, such as relays, involved CONSTITUTION:The title operation circuit consists of a rectifying circuit 2 which rectifies the alternating current from an ac power supply 1; motor 8 driven by the output from the rectifying circuit 2; motor operation switch 4 provided in the power path between the rectifying circuit 2 and motor 8; relay 7, including contacts 5 and 6, inserted in the power path between the motor operation switch 4 and motor 8; and delay circuit 9, placed on the output side of the rectifying circuit 2, which, a specified time after the motor operation switch 4 being turned on, energizes the relay 7 and thereby makes the contacts 5 and 6

Hirotsune Koji

Papers

Electronic trip relay

Motor operation circuit