Sub-station components

Air break disconnect switches (mounted on the steel structure) These are used for maintenance.

Capacitive voltage transformers/voltage transformers (the one long candlestick-like device under the switches). These devices transform the line voltage down to a voltage low enough to be used by relaying and metering devices that protect and monitor the substation. In this case, the incoming line voltage is being monitored.

Line trap (the thing with a cylinder on it). This device is used in older communication systems where the communication is transmitted across the transmission line (power line carrier technology-PLC). Nowadays, fiber optic technology would be utilized. This device acts in concert with the capacitor in the voltage transformer to create an short circuit for PLC frequencies so that they do not travel through to the equipment in the substation, and create heat inside the equipment. The communication used in a substation is for relay operation and other data (metering, substation status information substation remote control, and relaying operations/monitoring). This communication/monitoring/relaying control is called the substation SCADA system (supervisory control and data acquisition).

Capacitive voltage transformers/voltage transformers (the three long candlestick-like devices near the line trap). These devices transform the line voltage down to a voltage low enough to be used by relaying and metering devices that protect and monitor the substation. In this case, the bus voltage between the line and the transformer high side is being monitored. The capacitor in the voltage transformer, together with the line trap, which is essentially an inductor, together make up an LC filtering circuit that creates a short circuit for communication frequencies from the power line carrier.

Disconnect air break switches (devices under the steel structure).

SF6 Transmission circuit breaker. This device opens under fault conditions in order to protect major equipment and to isolate the parts of a substation that is malfunctioning. In large substations, the breakers would be configured in such a way as to enable the healthy parts of the substation to continue to operate while isolating the parts that are affected by electrical faults or other issues like equipment failure.

Capacitive voltage transformer-used to monitor the voltage on the high side of the transformer for relaying and status purposes.

Three single phase transformers. Older substations used three separate transformers connected in a wye or delta configuration depending on the voltage.

In the background from left to right,

Behind the first voltage transformers are near the switches mounted on the steel structure, the device with the brown insulators on it is a circuit breaker.

Behind the circuit breaker in point 1 is a three phase transformer (all phases inside one tank as opposed to three separate transformers).

Behind the three phase transformer in point 2 is either a control enclosure with relaying /SCADA/communications equipment, or it is distribution switchgear. The distribution switchgear would contain circuit breakers and relaying/communication for the distribution side/low side of the substation. It’s hard to tell which it is, though.

Near the three capacitive voltage transformers are located, it appears that the device behind them is a three phase transformer, but it’s hard to see it.