Designing Of Over-Temperature On-Line Detecting Apparatus For Isolator In High Voltage Switchgear Cabinet

Over-temperature of isolator in high voltage (HV) switchgear cabinet can initiate power failure, even fatal accidents. So on-line over-temperature detecting for isolator is an advanced task to protect safe operation of high-voltage devices.Considering the limitation of current over-temperature detecting apparatus for isolator, this thesis presents a novel method for indirect over-temperature detection of isolators in HV switchgear cabinet based on a new-type polymer labels and Na Superionic Conductor CO₂ sensor. The over-temperature detecting principle is put forward and an over-temperature detecting apparatus based on the method is introduced. The detecting apparatus is consisted of new-type temperature-indicating polymer labels, MS4100 CO₂ gas sensor, signal condition circuit, single-chip microprocessor MSP430F149, alarming circuit and system operating software. In the hardware designing section, mainly introduced primary modules and some measures for improving reliability; and in the software designing section, introduced the proimary software modules and some measures for improving precision.A temperature compensation circuit is adopted to eliminate the influence of temperature. In view of the characteristics of rude signal, an appropriate method of real-time digital filtering is used to improve the signal-to-noise ratio (SNR). The difference features of the signal under over-temperature condition have been analyzed and compared to those under normal condition. The thesis introduced a reliable algorithm for identify over-temperature detection based on sequential section difference.In order to maintain performance reliability and anti-interference of the apparatus,effective anti-interence measures of hardware and software have been introduced.In the end, debugging of on-line detecting apparatus and experiment conditions, method are introduced. The experiment data were anailzed. Test is carried out, results showed us that the apparatus is long-term stability and reliable. The isolators over-temerature alarming is acquired of based on on-line detecting apparatus.