Oil and GasTraditionally, local flow metering was done using high maintenance mechanical circular chart recorders. Today these have been replaced with electrically powered Remote Terminal Units (RTU). Multiple remote terminal units communicate to a central host system via radio systems or tap into the cellular phone system. The host (or central control room) communicates with the RTUs and radio communication infrastructure is referred to as a Supervisory Control and Data Acquisition (SCADA) system. In addition to gas flow metering, the RTU also provides some local, self-contained, site control such as well shut-in in the event of abnormal gas flow conditions. However the bulk of the RTU's function is to provide the host with site specific data which includes the above mentioned gas flow metering data, plus process related data including pipeline and/or well pressure, condensate tank levels etc. Not All RTUs Are The Same The distinguishing feature of the remote gas well RTU is a "gas flow computer". This is essentially a sophisticated subprogram or flow computer algorithm. The oil well RTU is much less complex since liquid oil flow metering is simpler. In the case of electrical utility RTU, there is a critical need for precise event time monitoring so that the first breaker to trip (closest to the fault) can be determined. As these sites are remote such that utility electrical power is rarely available, the RTUs must be powered by an array of solar panels plus batteries. The batteries enable the RTU to continue to function when the sun is below the horizon or is obscured by heavy cloud cover. These RTUs also must be extremely rugged and energy efficient, i.e., must function to −35 °C. Energy efficient RTUs vastly reduce the cost of the solar battery system especially at higher latitudes. Protection of RTU’s Protection of RTUs must meet environment protection specified for each site according to local standards and field regulation. International Hazardous location standards, ATEX directive, NEC, CSA, BASSEFA, UL, FM and more. All RTU’s structures and protection must comply with site standards. MDA / Satel Solutions Standardized RTU’ based on UHF or VHF Satel Data modems combined with independent power supply and power conversion options for grid power, solar power and battery backup. The I/ O module is a Modbus based 16, 32 or 64 I/O modular system. RS 485, 232 are standard, Profibus DP is optional. Other system conversion is available upon request. Modems are powerful available in 1W to 35W and range up to 50 miles in open sea or line of site.