load profiles of consumer meters and of the substation input meter; a single-line diagram of the 0.4 kV network: consumer connection points, poles and nodes; line sections: conductor or cable type, installation (overhead or underground), approximate length. The diagram can be drawn in the GRID-IN editor on a map, including from a phone right at the line, or supplied as a file. Details — Data requirements.

Technical loss calculation for 0.4 kV networks

Q: What do technical losses depend on?

current — losses grow with the square of the current: double the current, four times the losses; section resistance — length, cross-section and material of the conductor or cable, and its temperature: a conductor heated by current and hot weather has higher resistance; how uneven the load is over time — for the same daily consumption, a peaky load causes more losses than a flat one; phase unbalance — with unequal phase loads current also flows in the neutral, and losses are higher than with the same load split evenly. Illustrative example. Two consumers each use 24 kWh a day. The first draws a steady 1 kW every hour. The second draws 4 kW for 6 hours and nothing the rest of the time. The energy is the same, but the second one’s current in those 6 hours is four times higher, and the losses on its line over the day are four times higher: 6 hours × 16 versus 24 hours × 1.

Technical losses are the energy spent heating lines, cables and the transformer. Every network has them, and no field visit can “find” them — they can only be calculated and reduced by network work. Until technical losses are calculated, it is impossible to say what part of the substation imbalance is non-technical.

What do technical losses depend on?

current — losses grow with the square of the current: double the current, four times the losses;
section resistance — length, cross-section and material of the conductor or cable, and its temperature: a conductor heated by current and hot weather has higher resistance;
how uneven the load is over time — for the same daily consumption, a peaky load causes more losses than a flat one;
phase unbalance — with unequal phase loads current also flows in the neutral, and losses are higher than with the same load split evenly.

Illustrative example. Two consumers each use 24 kWh a day. The first draws a steady 1 kW every hour. The second draws 4 kW for 6 hours and nothing the rest of the time. The energy is the same, but the second one’s current in those 6 hours is four times higher, and the losses on its line over the day are four times higher: 6 hours × 16 versus 24 hours × 1.

Why are monthly totals not enough?

A calculation from the average monthly current underestimates losses: it misses the peak hours, when losses are highest, and it misses phase unbalance. AMI data gives the hourly or half-hourly load of every meter, so losses are calculated for every interval and summed.

What does GRID-IN calculate?

losses in the substation transformer and in every overhead and cable section — for the period and by hour;
loading of every section against its continuous current rating — overloaded sections;
voltages at nodes and at consumers, voltage drop to remote consumers;
the split of the substation imbalance into technical and non-technical losses;
with per-phase meter readings — a calculation for each phase, neutral losses and load unbalance (see Consumer phase identification).

The network is calculated as an electrical circuit from the diagram and the meter profiles, taking into account that conductor resistance depends on air and ground temperature. GRID-IN determines consumer phasing, node voltages and refined line lengths itself. The diagram is coloured by losses and loading, so the worst places are visible at once.

What is needed?

load profiles of consumer meters and of the substation input meter;
a single-line diagram of the 0.4 kV network: consumer connection points, poles and nodes;
line sections: conductor or cable type, installation (overhead or underground), approximate length.

The diagram can be drawn in the GRID-IN editor on a map, including from a phone right at the line, or supplied as a file. Details — Data requirements.

How can technical losses be reduced?

rebalance consumers across phases where loads are unbalanced;
replace conductors on sections loaded close to their rating;
connect a large consumer closer to the substation or from another feeder;
compare losses before and after — by recalculating on new data.

The overall plan — How to reduce losses in 0.4 kV networks.

Can technical losses be calculated without a diagram?

Not accurately: without lengths and cross-sections the section resistances are unknown. Without a diagram GRID-IN detects non-technical losses from meter profiles and shows the imbalance without splitting it into technical and non-technical.