Overview
The Isolation Switch was designed and introduced by Dairyland to allow safe disconnection and reconnection of a Dairyland decoupling device without causing exposed arcing. The following article discusses some of the primary uses of the Isolation Switch.
¿Cuándo debe utilizarse el interruptor de aislamiento?
La principal necesidad del Interruptor de Aislamiento se produce cuando existe la posibilidad de que haya tensión de CA en los terminales del desacoplador, lo que puede dificultar la desconexión del desacoplador sin provocar un arco. Por este motivo, las aplicaciones en las que hay CA inducida, o puede haberla en el futuro, son buenas candidatas para el interruptor de aislamiento.
Usos prácticos del interruptor de aislamiento
Decoupler Testing
While the performance of Dairyland decouplers over the last 30 years has been impeccable, some users are required to perform periodic testing of decoupling devices to ensure proper operational condition of the Dairyland device. Some field tests recommended by Dairyland require temporary disconnection of the decoupler from the pipeline.
En situaciones en las que puede haber tensión alterna, la desconexión segura de un desacoplador puede ser un problema. El Interruptor de Aislamiento clasificado para corriente de defecto elimina los problemas de seguridad y convierte la desconexión/reconexión segura en un procedimiento rutinario.
Decoupler isolation from close interval survey (CIS) operations
In some instances, decouplers on well-coated pipelines can affect off-potential readings during close interval survey testing. The Dairyland PCRX, designed specifically to solve this challenge, is the perfect solution for these applications. For a detailed discussion of this issue and the PCRX, check out our technical article, Utilizing the PCRX to Address Capacitance Issues During CIS Testing.
Sin embargo, en algunos casos, el desacoplador debe ser desconectado del circuito. La operación simple del Interruptor de Aislamiento facilita al personal que hace CIS desconectar y reconectar el desacoplador de Dairyland durante la prueba de manera rápida y segura.
Isolation of high frequency signals from locators and coating defect instrumentation
Certain test equipment used on pipelines emits a frequency or uses rectifier cycling to perform its function. Examples include pipe locators, and ACVG and DCVG coating defect test equipment. The Dairyland decoupler will appear as a low impedance to 60Hz and higher frequencies (which is how it can perform AC mitigation) and will shunt this current to ground or to the other connected structure. Similar to the CIS discussion above, rectifier cycling can cause some small current flow in the decoupler during the on-off transition, and appear to ACVG and DCVG equipment as a coating defect. In cases of such decoupler effects, one or two decouplers on either side of the test location may need to be disconnected via the Isolation Switch.