Polyphase Transformer-Rated Application - Instant Video
SummaryThis 36-minute video examines transformer-rated installations and discusses where and why instrument transformers are used. Instrument transformer basics are reviewed, their polyphase connections are shown, and common polyphase transformer-rated installations are examined. Installation procedures are discussed, with close attention to transformer polarity markings. How to size, select, and verify in the field, correct CTs and VTs for a given job.
Polyphase Transformer-Rated Metering – 10 minutes
Describes the functions of the two basic types of instrument transformers commonly used in metering. Identifies variables that affect the installation of current transformers and meters.
Delta Transformer-Rated Meter Installations – 9 minutes
Describes a typical three-phase, three-wire, delta transformer-rated meter installation. Describes a typical three-phase, four-wire, delta transformer-rated meter installation. Describes one way to determine the instrument transformer requirements for a given delta transformer-rated meter installation.
Wye Transformer-Rated Meter Installations – 7 minutes
Describes a typical three-phase, four-wire, wye transformer-rated meter installation. Shows one way to determine the transformer requirements for a typical wye transformer-rated meter installation.
Instrument Transformer Verification – 10 minutes
Describes problems that can develop with instrument transformers. Shows how some of the electrical properties of instrument transformers can be checked. Demonstrates how a meter on a polyphase installation can be checked to ensure proper registration.