The invention relates to an online monitoring device for a turn-to-turn insulation fault of an air-core
power reactor, which is characterized by comprising a method for judging a turn-to-turn insulation fault of the air-core
power reactor through changes in value of a
loss factor. The online monitoring device is composed of a
signal extraction portion, a
signal conversion control portion, a
computer operation portion and a display and alarm portion, and is characterized in that
terminal voltage and current signals of a monitored reactor are extracted by applying a
voltage transformer and a
current transformer, the
terminal voltage and current signals are zoomed so as to conform to a
processing range of an AD converter, a single-
chip microcomputer controls the AD converter to perform
processing on analog
voltage and current signals, the processed analog
voltage and current signals are sent to a computer to perform analysis and calculation on a
loss factor, active power and reactive power are calculated through current and voltage signals, and the
loss factor is calculated; changes of the loss factor tan<
delta> is monitored online in real time, the loss factor tan<
delta> is compared with a loss factor tan<
delta> threshold under normal
power reactor running, a running state of the reactor is displayed, and an alarm is given out when the loss factor tan<delta> exceeds the threshold. The online monitoring device realizes online monitoring for the air-core power reactor; a detection objective is realized via the proposed method of being according to changes of the loss factor, thereby promoting and expanding a new direction of online monitoring for the air-core power reactor; and the running reliability of the air-core power reactor is improved.