Transformer comprehensive protection setting values?
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For a single 1250KVA transformer, would current quick-break protection, overcurrent trip protection, gas protection, and oil temperature alarm be sufficient as protections? How should the setting values for current quick-break protection and overcurrent protection be determined?
Overcurrent protection for transformers: (1) Set to avoid the maximum load current that the transformer may experience; (2) Set to avoid the maximum operating current resulting from automatic load switching under overload conditions; (3) Set to avoid the situation where loads are automatically connected to the transformer’s low-voltage busbar; (4) Set in coordination with adjacent protective devices. When the low-voltage side of the transformer is equipped with outlet protection, it should be coordinated accordingly. Current quick-break setting: 1. Calculate based on the maximum short-circuit current flowing through the protection during external short-circuit faults ； 2. Calculate based on avoiding the inrush current of the transformer (3 to 5 times the rated current of the transformer).
The setting values for overcurrent and quick-break protection, as well as their operating times, are specified in relevant regulations, and these values are determined based on the terminal impedance of the transformer； The protection setting values for transformers are generally determined by the power supply authority, so the poster doesn’t need to calculate them