Technical Article

When to Use a PCRX

Decouplers are a vital element of most CP systems, providing numerous benefits to their users including blocking the flow of DC current to ground, AC voltage mitigation, over-voltage protection, safety grounding and AC fault current and lightning impulse protection. For over 30 years, Dairyland has been providing the industry with leading decoupler technology in the form of the globally used SSD and PCR.

In some circumstances however, site conditions and other factors, along with traditional decouplers like the SSD and PCR, contribute a capacitive effect to interrupted surveys, which can lead to inaccurate readings and frustration for users. Dairyland has previously discussed solutions to these challenges, including adjustments to the instant off cycle times or disconnection of the decouplers using the Isolation Switch. The PCRX introduces new sophisticated camouflage technology that addresses these challenges without requiring disconnection or other time consuming methods of remediation.

 

When Do I Use the PCRX?

The capacitance effect that can lead to inaccurate interrupted surveys can be challenging to predict as it involves a variety of factors and site conditions.  While Dairyland has done extensive research using internal and external experts, there is not an easy one-size-fits-all answer.  However, general guidance in the selection of the decoupler is given below.

 

Compare Product Ratings

Dairyland’s range of decouplers all perform the same core functions of providing simultaneous DC isolation and AC grounding. However, there are differences in product ratings and features that should be evaluated when choosing a decoupler for your site conditions. Utilize the chart below to compare decoupler models and determine the most suitable product for your needs.

What Decoupler Do I Need

Note: The PCRX is currently certified to Division 2 requirements. International certification for Zone 2 requirements to be completed in early 2021.

 

Evaluate Site Conditions

Notably, the only decoupler featuring camouflage technology addressing capacitive effects during interrupted surveys is the PCRX. When evaluating what product to choose, an expected question arises: How do I know if my site will have this capacitive effect on my interrupted surveys?

Due to the wide variety of factors, it is not possible to predict with certainty which sites will experience this issue.  However, site conditions play a significant role in whether or not users will experience the capacitive effect during interrupted surveys with traditional decouplers.

While this cannot be used as a definitive tool, the following illustration shows a sliding scale indicating the likelihood of this effect occurring based on site conditions.  The PCRX will be suitable for any site condition.  Traditional decouplers like the SSD or PCR are less likely to have a significant effect on interrupted surveys in site conditions indicated on the left of this chart.

site conditions 2

Definitive Site Testing

CAD 270

 

While an analysis of the product ratings and site conditions is likely adequate for most users, some users may want a more definitive answer to whether ornot their site would benefit from the PCRX.  Dairyland has developed an in-depth process for site testing.  See the article Testing and Evaluation of Decoupler Capactive Effects and Utlization of the Dairyland Model PCRX’ for a thorough explanation of this process.  By utilizing existing standard decouplers or the new CAD-270 Capacitive Assessment Device, users can gather site data for this determination.  A general outline of this site evaluation method is below.

 

testing flowchart

 

If you are interested in learning more about this definitive site testing process prior to choosing a decoupler for your application, please contact Dairyland technical support for more information.

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