Model Number and Meaning
S13(22)-M.ZT On-Load Automatic Capacity-Regulating Distribution Transformer
Scope of Application
The S13(22)-M.ZT transformer is designed for three-phase power distribution systems with a rated frequency of 50 Hz and a voltage level of 10 kV. Its rated capacity range is from 100(30) kVA to 630(200) kVA.
Product Introduction
The S13(22)-M.ZT is an on-load automatic capacity-regulating distribution transformer with two rated capacity levels.
The automatic capacity-regulating controller continuously detects and evaluates the user’s load. According to the actual load level, a special on-load capacity and voltage regulating switch automatically changes the transformer between its two capacity modes without interrupting normal operation.
This automatic switching function allows the transformer to operate at the appropriate rated capacity under different load conditions.
Applications
The S13(22)-M.ZT transformer is suitable for locations with strong seasonal power demand, large load fluctuations, concentrated periods of electricity consumption and a low annual average load rate.
In rural power networks, electricity consumption is often concentrated during the summer and autumn seasons. Transformers may operate under overload conditions during busy agricultural periods, while the load rate can remain very low during other seasons.
The on-load automatic capacity-regulating transformer can change its operating capacity according to these load variations, making it particularly suitable for rural power grid upgrading projects.
It is also suitable for residential communities, enterprises and public institutions where there is a large difference between daytime and nighttime electricity demand.
Operating Principle
When operating at the larger capacity, the three-phase high-voltage windings are connected in a delta configuration, while the low-voltage windings operate in a parallel arrangement.
When operating at the smaller capacity, the three-phase high-voltage windings are connected in a star configuration, while the low-voltage windings operate in a series arrangement.
The star-delta conversion of the high-voltage windings and the series-parallel conversion of the low-voltage windings are completed by the on-load capacity-regulating switch. The automatic controller operates the switch according to the detected load level.
When the transformer changes from the larger capacity to the smaller capacity, the number of effective coil turns increases by approximately 1.7 times. This greatly reduces the magnetic flux density of the core and lowers the unit loss of the silicon steel sheets.
As a result, the no-load loss and no-load current are significantly reduced. The no-load reactive power loss at the smaller capacity is less than one-tenth of that at the larger capacity, while the no-load active power loss is less than one-third.
This operating method reduces unnecessary energy consumption and improves the transformer’s energy-saving performance under light-load conditions.
