What Does Polarization Cell Replacement (PCR) Mean?
A polarization cell replacement (PCR) is a solid-state device designed to concurrently provide DC decoupling and AC continuity/grounding when used with cathodically protected structures, such as:
- Grounding systems
- Cable casings
The solid-state design eliminates the maintenance requirements and the potentially hazardous electrolytes associated with polarization cells, making the PCR are an ideal replacement for electrochemical polarization cells.
Common PCR applications include:
- Insulated joint protection
- AC voltage mitigation
- Decoupling electric equipment grounding systems
- Decoupling from utility grounding systems
Corrosionpedia Explains Polarization Cell Replacement (PCR)
A polarization cell replacement is a solid-state device commonly used in conjunction with cathodically protected structures. The PCR has very high AC fault current and lightning surge current ratings. With a higher blocking voltage than polarization cells, the PCR eliminates the need for placing devices in series, making it the most ideal isolation and grounding product for cathodically protected structures. In addition to out-performing polarization cells, the PCR also surpasses metal oxide varistors and gapped arresters, clamping lightning-caused over-voltages to the lowest possible levels.
The operating parameters of PCR offer a number of distinct advantages. Because the device has a higher DC blocking voltage, one device can often replace two or more polarization cells. The product is easy to apply because its operating parameters are precisely defined.
By decoupling the cathodic protection (CP) system from grounding systems and other structures, the CP requirements can be minimized, while maintaining an effective ground or bond rated for AC faults and lightning current. They are generally maintenance-free, with no periodic service or testing requirements.
There are a number of applications where a PCR may be required to block DC while simultaneously carrying steady-state AC current. For example, when a pipeline is in the same corridor as an electrical transmission line, steady-state AC voltage is often induced on the pipeline. The PCR can mitigate this voltage by providing a low AC impedance path for AC current to flow to ground while simultaneously preventing the flow of DC current.
The PCR is designed to keep the voltage between the device terminals to a limited value. PCR is also available in submersible version.