... , it can transmit data from apparatus (thermometer, humidity meter, electric meter, flowmeter, PLC) to user or monitoring center by GPRS. The ... need switch on the air-conditioning immediately, or when water overflow and need switch on the dryer, or when ... saving,street lights control system;14. Tanks, levels, temperatures,water leakage applications;15. Transformer stations;16. Unmanned machine rooms; ...