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- Isolation Switch by Dairyland Electrical
When decouplers are installed on a pipeline for AC voltage mitigation and over-voltage protection, there may be occasions where disconnection of the decoupler is required. Safe disconnection cannot always be easily accomplished by hand if notable AC induction is present, therefore Dairyland designed the Isolation Switch to serve this need. Where such isolation is necessary, the Isolation Switch allows safe disconnection and reconnection without causing exposed arcs, in an AC fault-rated design.
ADDRESSES ISSUES SUCH AS
- Isolation of high frequency signals from locators and coating defect instrumentation
- Decoupler isolation from close interval survey (CIS) operations
- Decoupler testing
The Isolation Switch is suitable for field installation to any Dairyland model PCR* or SSD decoupler in a Dairyland pedestal. The Isolation Switch is also available in its own enclosure for field installation separate from the PCR or SSD.
*Not for use with PCR models rated 80A AC continuous.
Isolation Switch Operation
The Isolation Switch is suitable for field installation to any Dairyland model PCR* or SSD decoupler in a Dairyland pedestal. The Isolation Switch is also available in its own enclosure for installation separate from the PCR or SSD.
When the Isolation Switch is installed, the conductor that normally connects to the negative decoupler terminal will be removed and reconnected to a new terminal on the Isolation Switch. Between this terminal on the Isolation Switch and the decoupler negative terminal there are two parallel connection paths, each of which can be OPEN or CLOSED. One path consists of a movable copper link that is closed under normal operations (i.e., decou - pler connected to the pipeline). This link is designed to carry the full ac fault current rating of any DEI PCR or SSD model decoupler. The other parallel path consists of an enclosed toggle switch that is momentarily used to interrupt or reconnect any ac current present during the decoupler disconnection or reconnection process. This switch is capable of making or breaking 50Aac at 125Vac, but is not rated for the fault current capability of the decoupler; hence, the reason for the parallel link to carry any fault and or lightning current. In normal opera - tion, when the decoupler is connected to the pipeline, the copper link is to be CLOSED with the bolts on each end of the link tightened to 10-12 Ft.-Lbs and the toggle switch handle is to be UP in the OPEN position to prevent this switch from carrying ac fault or lightning current for which it is not rated.
For all product features and accessories, see full product literature and installation instructions.
*Not for use with PCR models rated 80A AC continuous. Contact Dairy - land for options.
Safety Considerations After the Isolation Switch has been installed, disconnec - tion of decouplers performing an AC mitigation function will cause the voltage on the pipeline to rise. NACE rec - ommends that exposed pipelines be limited to 15V for personnel safety. Therefore, appropriate user-approved and industry safety precautions should be taken whenev - er one or more decouplers are disconnected on a pipe - line subject to AC influence.
Note that the Isolation Switch is not certified for, and may not be used in, hazardous (classified) locations. Most AC mitigation sites in a right-of-way are not classified haz - ardous locations, which would allow Isolation Switch use, but the user must confirm the validity of any such instal - lation.
Dairyland provides suggested safety procedures for in - stalling and operating the Isolation Switch. When install - ing an Isolation Switch on a voltage mitigated pipeline, if one decoupler is isolated at a time to install the Isolation Switch, it is expected that the pipeline voltage will remain below the 15Vac NACE recommended limit at each in - stallation location, but if not, safety guidelines are provid - ed. The installer must follow these instructions in addition to all industry and company-specific safety practices.