Voltage transformers: Why modern CVTs don`t drift

Journal Article · Mon Apr 01 04:00:00 EST 1996 · Electrical World

OSTI ID:263146

Ribeiro, J ^[1]

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1. Haefely Trench, Scarborough (Canada)

Capacitive voltage transformers (CVTs) have some distinct benefits over wound voltage transformers for some applications, particularly at high-voltage classes. Initial cost is lower, they are less susceptible to ferroresonance, and they can also double as coupling capacitors for power-line carrier communications. But many engineers are reluctant to specify CVTs because of the perceived problem of drift. An understanding of how modern CVTs are built should alleviate concerns about accuracy drift. CVTs are composed of series coupling capacitors and an electromagnetic unit. The primary-to-secondary voltage ratio is achieved by combining the capacitor divider ratio with the intermediate transformer ratio. Because commercially manufactured capacitors of the same design vary slightly in total capacitance, the intermediate transformer and series reactor are equipped with voltage taps for final adjustment of the CVT. This paper discusses the factors that affect stability - including distance and dielectric constant, along with standards that CVT`s must meet. 4 figs.

• OSTI ID: 263146
• Journal Information: Electrical World, Journal Name: Electrical World Journal Issue: 4 Vol. 210; ISSN 0013-4457; ISSN ELWOA3
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
CAPACITANCE
DESIGN
DIELECTRIC PROPERTIES
ELECTRICAL EQUIPMENT
FILMS
STANDARDS
TRANSFORMERS