LRV (Lower Range Value) and URV (Upper Range Value) are settings used in digital transmitters to define the minimum and maximum values of the measurement range that the transmitter is calibrated to measure. These values correspond to the lowest and highest process variable (PV) values that the transmitter is expected to measure accurately within its specified range.

Here's what LRV and URV represent:

1. LRV (Lower Range Value):

   • LRV is the minimum value of the measurement range that the digital transmitter is calibrated to measure accurately.
   • It represents the lowest process variable (PV) value that the transmitter can reliably detect and measure.
   • LRV is typically set to the lowest expected value of the process variable in the application.
   • For example, if the process variable is pressure and the lowest pressure expected in the system is 0 psi, then the LRV would be set to 0 psi.

2. URV (Upper Range Value):

   • URV is the maximum value of the measurement range that the digital transmitter is calibrated to measure accurately.
   • It represents the highest process variable (PV) value that the transmitter can reliably detect and measure.
   • URV is typically set to the highest expected value of the process variable in the application.
   • For example, if the process variable is temperature and the highest temperature expected in the system is 100°C, then the URV would be set to 100°C.

Sensor Trim and Output Trim:

• Sensor Trim: Sensor trim involves adjusting the calibration of the transmitter's sensor to ensure accurate measurement of the process variable. It may involve compensating for sensor drift, non-linearity, or other factors affecting sensor performance. Sensor trim is typically performed during initial installation or periodic maintenance to maintain the accuracy of the transmitter over time.

• Output Trim: Output trim involves adjusting the output signal of the transmitter to match the desired range or scaling of the control system or monitoring equipment. It may involve linearizing the output signal, applying scaling factors, or adjusting zero and span settings to ensure compatibility with the receiving device. Output trim is often performed as part of the calibration process to ensure that the transmitter's output signal corresponds accurately to the measured process variable.

Overall, LRV and URV settings define the measurement range of a digital transmitter, while sensor trim and output trim are calibration adjustments made to ensure accurate measurement and output signal scaling, respectively. These settings and adjustments are crucial for maintaining the accuracy and reliability of digital transmitters in various industrial applications.