Technical Loss in Electrical Systems
Technical loss is inherent in electrical systems, as all electrical devices have a few resistances and the flow of currents causes a power loss (I2R loss). Integration of this power loss over time, i.e. ∫ I2R.dt is the energy loss. Every element in a power system (a line or a transformer) offers resistance to power flow and, therefore, consumes some energy although performing the duty expected of it. The cumulative energy consumed by all these elements is classified as "Technical Loss." Technical losses are because of energy dissipated in the conductors and equipment used for Transmission, Transformation, Sub- transmission and Distribution of Power. These occur at several places in a distribution system - in lines, mid-span joints and terminations transformers, service cables and connections and etc.
Table: Losses Due to Technical Reasons
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• Line losses
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• Loss in conductors/cables where lowersize conductors are used. This causessags and temperature rise in conductorswhich further aggravate the loss,
• Loss in higher loaded phase wires due to unbalanced loading,
• Loss due to current in neutral for cases or unbalance where neutral wires of lowersize are used (like 3 ½ core cables, andneutral wires of size lower than phasewires),
• Loosening of strands (in multi-strandconductors like ACSR, AAC, AAA, etc.).
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• Loss in mid-span joints
(or any joint) and at
terminations
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• Contacts of joints due to improper installation and looseness,
• Contacts of joints due to inadequatesurface area of contact.
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• Loss in transformers
(typically DTs)
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• Loose connections at bushings,
• Bend in jumpers at connectors where the strands are not tightly held,
• High no-load loss depending on type of core used,
• High no-load loss in repaired transformers where the core has not been properly tightened,
• No load loss in case a large number of lightly loaded DTs,
• High copper loss for transformers operating at sub-optimal loading which is not commensurate with the designed optimal loading.
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• Loss in service cables
and connections
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• Undersized service cables,
• Loss in joints of service cables at the poles/junction boxes,
• Use of inappropriate fasteners without spring washers at the crimped joints.
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• Loss due to high
impedance faults
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• Tree touching, creepers, bird nesting,
• Insulator breakages and tracking on surface of the insulator.
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• Loss in re-wired
fuses/jumpers
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• Loose connections,
• Inadequate size of fuse wires - often a source of hot spots.
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The magnitude of energy dissipation depends hugely on the pattern of loading of transmission and distribution lines, kinds of loads, design of lines and etc. It is not probable to eliminate such losses inherent in a system altogether. They could, thus, be reduced to some extent. The technical losses could be further sub-grouped depending upon the stage of power transformation and transmission system as Sub-transmission losses (33 kV/11kV), Transmission losses (400 kV/220 kV/132 kV/66 kV), and Distribution losses (11 kV/0.4 kV).