Thermal stability and dynamic stability multiples: When the power system fails, the Electrical Current Transformer is subject to the thermal and electrodynamic effects of the huge current caused by the short-circuit current. The Electrical Current Transformer should have the ability to withstand without being damaged. This ability to withstand Thermal stability and dynamic stability multiples. The thermal stability multiple refers to the ratio of the current that does not cause the electrical current transformer's heat to exceed the allowable limit within 1s of the thermally stable current to the rated current of the Electrical Current Transformer. The dynamic stability multiple is the ratio of the maximum instantaneous current value that the Electrical Current Transformer can withstand to its rated current.