Distribution Remote Terminal Units (RTUs), Distribution Terminal Units (DTUs), and Transformer Terminal Units (TTUs) serve distinct functions in the electrical industry. Let's delve into their differences.

DTU (Switchgear Terminal Unit):

DTUs are typically installed at conventional substations, outdoor small-scale substations, ring main units, small substations, or compact substations. They collect and calculate data such as position signals, voltage, current, active power, reactive power, power factor, and energy consumption from switchgear equipment. DTUs also perform operations like circuit switching, fault identification, isolation, restoration of power supply in non-faulty intervals, and some models may include protection and automatic backup power source activation functionalities.

FTU (Feeder Terminal Unit):

FTUs are monitoring devices installed adjacent to feeder switches, usually outdoor pole-mounted switches like circuit breakers, load switches, and sectionalizers on 10kV lines. Typically, one FTU monitors one pole-mounted switch, especially in cases of dispersed installations. In situations where switches are mounted on the same pole, one FTU can monitor two switches.

TTU (Transformer Terminal Unit):

TTUs monitor and record the operational status of distribution transformers. They calculate parameters such as voltage, current, active power, reactive power, power factor, active energy, and reactive energy based on sampled values of low-voltage side three-phase voltage and current at intervals of 1 to 2 minutes. TTUs store recorded data for a period (e.g., one week or one month) and store typical daily values of measured parameters. The data is retained in non-volatile memory, ensuring data integrity even during power loss. Distribution main stations retrieve TTU measurements and historical records via communication systems to promptly detect issues like transformer overload and power outages. The recorded data is also used for statistical analysis, load forecasting, distribution network planning, and fault analysis.

In summary, while DTUs handle switchgear operations, FTUs monitor feeder switches, and TTUs focus on transformer monitoring and data collection. Each plays a vital role in ensuring the reliability and efficiency of the distribution network.