ΣCT
Summation current transformer
Auxiliary CT with several primary windings that adds the secondary currents of other CTs into one output.
Schematic / SLD
Symbols · Σ kWh
Summation energy meter
Integrating device that adds energy from several meters or circuits to give one total register.
In plain English
What does Summation energy meter mean?
A summation meter totalises energy from more than one circuit. It may count pulses from several transmitting meters or, in older schemes, be fed by a summation CT, and it appears where several incomers or feeders must be billed or monitored as one supply.
A simple example
Every input must use the same direction convention and consistent pulse weights, or the total is wrong. The symbol shows the summing function but not the inputs, so each source meter should be listed with its weighting.
What the drawings help you do
List every meter or circuit that feeds the total. Check pulse weights and directions are consistent. A summation meter totals several circuits; a summation CT adds currents before measurement.
This particular reference
Integrating device that adds energy from several meters or circuits to give one total register. A summation meter totals several circuits; a summation CT adds currents before measurement.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: IEC graphical symbols for diagrams · Power and energy measurement quantities
SLD / Schematic · Σ kWh
What it represents
A summation meter totalises energy from more than one circuit. It may count pulses from several transmitting meters or, in older schemes, be fed by a summation CT, and it appears where several incomers or feeders must be billed or monitored as one supply.
Every input must use the same direction convention and consistent pulse weights, or the total is wrong. The symbol shows the summing function but not the inputs, so each source meter should be listed with its weighting.
How to read it
- List every meter or circuit that feeds the total.
- Check pulse weights and directions are consistent.
Information to show or reference
- List input meters
- State weighting per input
- Define direction convention
A distinction that matters
A summation meter totals several circuits; a summation CT adds currents before measurement.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
IEC graphical symbols for diagrams
IEC context for graphical symbols used in diagrams; no IEC graphic is reproduced.
Power and energy measurement quantities
Public explanation of energy and power measurement quantities used by meters.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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