An effectively grounded three-phase insulated electrical fire online prevention and control device and method

Abstract

The invention discloses an effectively grounded three-phase insulation type electrical fire online prevention and control device and method. The prevention and control device of the invention includes a DSP unit, a single-chip microcomputer module, a photoelectric coupler module, an alarm unit, a control output unit, and an Ethernet communication unit. Unit, reset circuit module, residual current signal detection module and conditioning circuit module, voltage signal detection module and conditioning circuit module; the prevention and control method of the present invention adopts the prevention and control device to decompose and restore the effective grounding three-phase AC power distribution system power supply circuit aggregate The residual current is sent to each phase, and the resistive residual current component that really represents the insulation characteristics of each phase is extracted, and the resistive insulation resistance of each phase is further calculated to realize online monitoring of the insulation performance and potential of the power supply circuit of the effectively grounded three-phase AC power distribution system. Electrical fire hazards, effectively preventing the occurrence of grounding short-circuit faults and electrical fire accidents, and the invention can overcome the defects of false positives and negatives and inability to detect online in conventional methods.

Description

technical field [0001] The invention belongs to the field of electrical fire prevention and control, and relates to an effectively grounded three-phase insulation type electrical fire online prevention and control device and method. Background technique [0002] In the power supply circuit of the effectively grounded three-phase AC power distribution system, the insulation performance of the cable and load insulation layer, and the decrease of the resistive insulation resistance value to the ground will lead to grounding short-circuit faults and even cause electrical fire hazards, threatening people's lives and property safety. . [0003] At present, the common insulation-type electrical fire prevention and control methods for effectively grounded three-phase AC power distribution systems include the loop residual current method and the megohmmeter method. The loop residual current method is to monitor the lumped residual current effective value IR of the power supply loop ...

AI Technical Summary

Problems solved by technology

Due to the relative ground capacitive insulation resistance (C a ,C b ,C c ) formed capacitive residual current component (effective value is IRc a , IRc b , IRc c ) will change at any time with the length of the cable laying, the unbalanced degree of each phase line to the ground, the number of loads, the ambient temperature and humidity, and the service life. In larger cases, their vector sum (effective value is IR Z ) may still exceed the lower limit alarm threshold and cause false alarms. Similarly, although the resistive residual current component is large and the capacitive residual current is small, their vector sum (the effective value is IR Z ) still may not exceed the lower limit alarm threshold, resulting in the occurrence of missing alarms

The megohmmeter method is to use the megohmmeter instrument to measure the insulation resistance off-line after the power supply circuit of the effectively grounded three-phase AC power distribution system is cut off. Relatively resistive insulation resistance value is less than insulation resistance lower limit alarm threshold R 0 (set according to the actual situation of the construction site or the relevant national standards), it is considered that the power supply circuit of the effectively grounded three-phase AC power distribution system has a grounding short circuit fault and a potential electrical fire hazard, and this method cannot be monitored online. and potential electrical fire hazard disadvantages

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