| 摘要 |
The invention relates to electrical engineering and could be applied for defending of relays and automation equipment. Its aim is to control temperature of contact outlets of distribution wires in the terminal box. Voltage divider 1 is connected to the supply of the terminal box. The output of the divider is connected to the single-phase bridge rectifier 2 with posistor 4 and capacitor 5 in series, the charging and discharging processes of which are formed by help of switch resistor 6 and transistor 7. Control resistor 8 is swiched in the discharging circuit of capacitor 5 and connected to the local responding part 9 of protective relay 10. The amplitude of the capacitor signal during the discharging process depends only on its accumulated energy defined with resistance of posistor 4. The increasing of its resistance depends of the temperature increasing of the connecting wires. With a particular decreasing of the signal amplitude the local responding part 9 of the protection relay is unlocked. The technical solution offered allows to avoid ignition of distribution wires of contact outlets.
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