Wide-dynamic-range residual current protection device

Abstract

The invention discloses a wide-dynamic-range residual current protection device which is composed of a composite residual current transformer, a residual current small-signal detection control drive circuit, a residual current large-signal detection control drive circuit, an execution unit and a trip coil, wherein the composite residual current transformer is composed of a composite iron core and two sets of mutually independent secondary windings; the two sets of secondary windings are respectively connected with the input ends of the two residual current signal detection control drive circuits; and the composite iron core is composed of a permalloy belt and a silicon steel sheet tape which are wound piecewise. The residual current protection device not only can accurately detect mA-level residual currents, but also can detect ampere-level residual currents, and the dynamic range can be up to 106, so that the residual current protection device can achieve a protection effect on people having electric shocks or equipment having electric leakage accidents, and also can achieve a protection effect on electric equipment having accidents caused by larger residual currents generated by earth faults.

Description

technical field [0001] The invention relates to the technical field of residual current protection, in particular to a residual current protection device with a wide dynamic range. Background technique [0002] For the circuit block diagram of the existing residual current protection device, see figure 1 shown. The device consists of a residual current transformer 1 with a single core material, a residual current signal amplification and detection unit 3, a residual current signal identification control and drive unit 4, an execution unit 5 and a tripping coil 6. The amplification detection unit 3, identification control and The DC working power of the drive unit 4 and the execution unit 5 is provided by the three-phase four-wire (A, B, C, N) power supply main circuit after being rectified by the rectifier 7 . [0003] The residual current transformer (ZCT) 1 as a residual current sensing device is generally composed of an iron core 1-1 wound with a single permalloy strip ...

AI Technical Summary

Problems solved by technology

[0009] It can be seen from the analysis that the iron core 1-1 of the residual current transformer 1 made of Permalloy ribbon or ultrafine-crystalline alloy ribbon can have high sensitivity for detecting mA-level residual current, but due to its saturation magnetic induction The intensity is not high, usually 0.5~0.6 Tesla, which leads to the distortion of the I△ signal collected from the secondary winding of the ZCT when a large residual current occurs, and the amplitude decreases. This situation will cause the residual current protector to Inability to act or "trip", resulting in a misjudgment

[0010] The value of residual current I△ formed by human body electric shock and electrical leakage of electrical equipment is generally mA level (5mA~1000mA), although the serious grounding fault current of electrical equipment can sometimes be as large as several amperes or above, for example, a single Phase-to-ground fault, but due to the above-mentioned "magnetic saturation" of the iron core, the value of the residual current I△ value induced by its secondary winding 1-2 is sometimes far from the rated operating current value of the residual current circuit breaker, so the circuit breaker It will not act (execute tripping), and it will not play a protective role

Therefore, if this problem is not solved, it will bring about disastrous consequences such as "fire"

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