Remote level sensor reading using the MT-101 telemetry ... - Inventia

A shielded 2 wire LIYCY cable is used to connect the level sensor to the telemetry
system. The dam on which the sensor is mounted is situated in a valley where the
GPRS signal level is very weak. Because of this an Inventia TELESAT-2 DUAL
antenna is used to enhance the quality of the GPRS signal. All the components of the
telemetry system were placed in a IP55 metal box which was mounted on a electricity
pole situated 35 meters away from the water dam. Fig. 2 present pictures of the
telemetry system.
Pg. 2/6
Fig. 2 Telemetry system pictures
Since the cable which connects the level sensor to the MT-101 module is very long the
current value read from the sensor drifts from the ideal value as the current increases.
In order to have accurate measurements five reference readings were taken from the
sensor for 4, 8, 12, 16 and 20mA and, based on these readings, a calibration function
was computed. This function was afterwards programmed into the MT-101 module
using the MTprog application. Fig. 3 presents the ideal and measured current values
before the calibration and Fig. 4 presents the ideal and calibrated current values.
S.C. PSC Automatizări şi Instalaţii S.R.L.
8B/19 Negoiu Street, Cluj‐Napoca, 400676, Romania
Tel.: 0745 140 767, 0743 074 332
office@psc‐asi.ro, www.psc‐asi.ro