"A" Station Turbine Basement
Electromechanical Watt-Hour Meter
The Electromechanical Watt-Hour Meter
being stored on the ground floor of "A Station"
The Metropolitan-Vickers Type ‘NE’ Polyphase Watt-Hour Meter setup is mounted above a set of Type PB Overcurrent Relays. Together, they formed part of a protective metering panel at the power station, helping to monitor and protect the electrical system.
The Type ‘NE’ meter was designed to measure how much electricity was used over time in a three-phase, four-wire AC system. Inside the meter, special coils respond to the flow of electricity and generate magnetic fields. These fields make an aluminium disc spin, with the speed of the disc reflecting the power being used at that moment. As it spins, a mechanical counter keeps track of the total energy consumed, measured in watt-hours (Wh).
These meters were typically used to monitor auxiliary systems or individual circuits supplied by the main generators. They were found in the power station’s generator feeder panels, turbine auxiliary boards or motor control centres, where they helped operators track power usage from the control room.
Mounted just below the meter are the Type PB Overcurrent Relays. These are electromechanical safety devices that protect the system by detecting when the electrical current goes above safe limits. If that happens, the relay triggers a breaker to shut off power to the affected circuit, preventing damage or fire.
Each relay is tied to one phase of the three-phase system and includes:
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A graph that shows how long the relay will take to trip depending on how high the current is,
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A dial to adjust the time delay (called the time multiplier),
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A plug setting to choose the trip current level and
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An internal mechanism that controls the trip function.
This type of equipment was widely used from the 1930s to the 1950s and many units remained in service for decades. Prior to the power station’s closure, these meters and relays were starting to be replaced with more modern digital systems.
The green-painted steel frame originally held the instrument panel that contained the electromechanical watt-hour meter.
Coal Chute Screen (TBC)
This metal structure may have originally been used on a coal chute, where coal was directed into a hopper or furnace. However, someone familiar with the site also suggested it could have been part of the ash sluicing system, acting as a screen mounted above the feeder that directed ash into a slurry tank for pumping away.
The curved, segmented casing suggests it was designed to channel material using gravity, with a possible inspection opening at the top for maintenance or monitoring.
The bolts visible on the side are likely the original mounting points, showing where the structure was once attached to a larger steel frame.
