PURPOSE: To reduce the size of facilities and to realize space reduction and economization, by incorporating an equivalent resistor for generating heat equivalent to heat loss generated in a large-capacitance capacitor device, in the tank of said device.

CONSTITUTION: The resistor 16 for generating heat equivalent to heat loss generated in the large-capacitance capacitor device 3 is stored in the tank of the device 3. During a test of a temperature rise, a changeover switch 17 is connected to the resistor 16, and during the operation of the device 3, the switch 17 is connected to a capacitor body 1. Consequently, the need for a compensating reactor in temperature rise testing facilities is eliminated, an inductive voltage regulator and a testing transformer are reduced in capacitance, and electric power is saved.