GESTRA LRG 16-60, LRG 16-61, LRG 17-60

Measuring process of the LRG 16-60 and LRG 17-60
LRG 16-60 and LRG 17-60 conductivity electrodes use the conductometric two-electrode measuring process. A measuring current with a suitable frequency for the measuring range is introduced into the fluid. This produces a potential gradient between the electrode and the measuring tube, which is analysed as a measuring voltage.
Measuring process of the LRG 16-61
The LRG 16-61 conductivity electrode use the conductometric four-electrode measuring process. It consists of two current and two voltage electrodes. The current electrodes introduce a measuring current with a fixed frequency into the fluid. This gives rise to a potential gradient between these electrodes. This potential gradient is then picked up by the voltage electrodes and analysed as measuring voltage.
Temperature compensation of readings based on a reference temperature (25 °C)
The electrical conductivity changes as a function of the temperature. In order to base the readings on a reference temperature, an integrated resistance thermometer measures the temperature of the fluid. The electrical conductivity is calculated from the measuring current and measuring voltage, and then based on the reference temperature of 25 °C through temperature compensation.
Compensation process
Based on a set temperature coefficient, the conductivity reading is corrected to form a linear characteristic. The coefficient (default 2.1 % per °C) is normally used for steam generating units with a constant pressure.
Behaviour in the event of an alarm
The alarm state indicating that a limit has been exceeded is shown on the display as “Hi.C” alternating with the actual conductivity value. The alarm is transferred to the URS 60 or URS 61 safety control unit via CAN data telegram. Once the time delay has elapsed, the alarm signal triggers the safety shutoff in the safety control unit. The URS 60 or URS 61 safety control unit does not perform lockout automatically. LEDs 1 and 4 indicate a MAX alarm.
Automatic self-test
An automatic self-test periodically monitors the safety and function of the conductivity electrode and measured value acquisition. The data are transferred to the URS 60 / URS 61 safety control unit in the form of a Black Channel data telegram in the CANopen protocol via an ISO 11898 CAN bus.