Practical Instrument Electronics (PIE) PIECAL 311Plus offers powerful troubleshooting tools that offer visibility to the health of your loop that is not possible with any calibrator brand on the market. Ground Leak Detection allows technicians to find and fix undetected problems before they become catastrophic failures - ending in injury, loss of life, equipment damage and lost product. Common loop problems caused by moisture, corrosion and contamination left unchecked can lead to dangerous conditions that are easily avoided with the innovation technology in the PIE 311Plus.