Andrew S. Sweetana

Transient Response Characteristics of Capacitive Potential Devices

Full voltage line to ground fault tests are performed on typical potential devices and the subsidence transient recorded. To show the worst case of residual voltage, faults are initiated while the primary voltage is passing through crest and zero.

A Procedure for Estimating the Lifetime of Gapless Metal Oxide Surge Arresters for AC Application

The development of the gapless metal oxide (ZnO) surge arrester has presented the arrester engineer with new materials and an opportunity for new designs. This situation arises because the gapless surge arrester is electrically active throughout its lifetime whereas its predecessor, the silicon carbide arrester, was electrically passive since it was electrically isolated with gap structures. The prime consideration is one of reliably estimating the lifetime of a gapless ZnO surge arrester under continuous ac stress while maintaining the capability not only to limit surge voltages but also to absorb energy inputs resulting from lightning or switching surges and temporary overvoltages. In this paper we establish a procedure for estimating the lifetime of gapless ZnO surge arresters for ac application by incorporating the device characteristics into design requirements. This method is illustrated for ZnO-surge-arrester elements that exhibit a predictable linear resistive current versus time?? behavior as a function of applied voltage and temperature.

Design, Development and Testing of 1200 kV and 550 kV Gapless Surge Arresters

This paper outlines the objectives of the EPRI development program on the 1200 kV and 550 kV gapless metal oxide arresters. Six important design considerations are described along with the verification testing involved with each. Final test results are presented on the individual arrester units as well as the complete 1200 kV and 550 kV poles.

A New Metering Accuracy Capacitive Potential Device

Previous designs of capacitive potential devices are briefly reviewed with an explanation of why they were not suitable for revenue metering. A new design metering accuracy potential device, capable of meeting 0.3-accuracy class at 400 VA, is presented. Theoretical error formulas are developed and confirmed by actual test results. Adverse effects such as temperature change, frequency shift, voltage change, rainfall, and contamination are considered. Transient response and ferroresonance tests are included.