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Power Service Neutral Isolator Design
	Power neutral isolator designed around a Joslyn gas tube (sparking device). Nearly 1300 units of this plastic case design were deployed. This isolator differs in performance and characteristics from those used in farm stray voltage mitigation (electronic switch and saturable reactor).
	Neutral isolator lid moved aside exposes one aluminum plate attached to one electrode of the gas tube. The other electrode has a similar aluminum plate.
	The aluminum plates act as heat sinks to drain heat from the sparking electrodes during a conduction, thus extending the operating envelope of the device so as to coordinate with transformer fuses.
	Heat dissipation tests were conducted to assess performance. Materials other than air, used in above design, were considered to increase heat dissipation. In this case, the gas tube was immersed in topping compound inside a steel container. The wires visible in the picture are thermocouple wires for temperature monitoring.
	In this instance, the gas tube was immersed in a bath of transformer oil inside a steel tank.
	The gas tube was buried inside an epoxy block in this case.
	In this trial, the gas tube is in the original air filled mode but includes a conformal plastic coating. Another problem experience in the field is moisture that inevitably enters into the sealed box. The moisture create resistive paths between the electrodes.
	Modified design used recently. Gas tube with aluminum plates is immersed in potting compound inside a steel container. The potting compound improves thermal dissipation and eliminates moisture problems.

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` Last updated: June 5, 1998.