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.

Masakatsu Suzuki

Papers

Electronic trip relay