CN2580650Y - Open-phase protector for AC motor - Google Patents

Abstract

The utility model discloses a phase-absent protector of an AC motor, which comprises a negative sequence filtered circuit, a single-phase rectifier circuit, a three-phase rectifier circuit and an action circuit, wherein, the action circuit is composed of a photoelectric relay, an ordinary relay and a tripping device. The utility model is suitable for various conditions that when electricity is directly supplied for a three-phase motor and no transformer is provided, phases are broken and when transformers with various magnetic structures are used for supplying electricity for the three-phase motor, phases of an original side and an auxiliary side are broken through various connection modes, etc. The utility model adopts the photoelectric relay and realizes the accurate judgement of action signals; simultaneously, a detection circuit is separated from the action circuit; because novel integrated components are adopted, the utility model has the advantages of simple circuits, reliable action, low cost, small size and only about 4.2*3.2*2 cm of a main circuit board. The utility model can be directly installed in an air switch; the utility model is quite suitable for the improvement and the upgrades of the existing equipment and the utility model can meet the requirements of various users.

Description

The alternating current machine phase failure protector

The utility model belongs to a kind of alternating current machine phase failure protector.

Alternating current machine principle that phase failure protector adopts mostly is greatly to detect motor three-phase input current signal or detect zero sequence signal and judges whether the phase failure at present, cuts off the electricity supply then.The method that wherein detects motor three-phase input current signal exists installs complicated problems, and detects the problem that there is the zero line potential drifting in zero sequence signal.In addition, under long situation apart from high voltage power transmission (as the oil production machine in oil field), need will power to motor after the step-down of high-tension electricity process transformer, this moment is if the phase failure of transformer secondary still can be adopted above-mentioned guard method; If the transformer former limit phase failure; the principle of above-mentioned guard method is then no longer suitable; this moment secondary electric current and zero sequence signal not only with former limit break separate relevant; also relevant with the connection (Y connection, Δ connection and neutral grounding mode) and the magnetic structure of transformer of transformer; the situation more complicated, the protection of above-mentioned principle can be lost efficacy under many circumstances.Adopt the negative phase-sequence signal can address the above problem as the protector of basis for estimation, but the circuit complexity of this type of protector at present, volume is big, and the cost height can not satisfy client's demand.

The utility model solves the above-mentioned problems in the prior art exactly; provide a kind of employing negative phase-sequence signal as basis for estimation; circuit is simple, and volume is little, in all cases the alternating current machine phase failure protector that can both play a protective role to the open phase fault of motor.

For addressing the above problem, technical solution of the present utility model is: a kind of alternating current machine phase failure protector, and it comprises that negative phase-sequence filters circuit, single phase rectifier circuit, rectified three-phase circuit and actuating circuit; Actuating circuit is made up of photoelectric relay, common relay and release; Negative phase-sequence filters the light-emitting diode of the output of circuit by single phase rectifier circuit connection photoelectric relay, be connected between the positive and negative electrode of rectified three-phase circuit after the coil of often opening node and common relay of photoelectric relay and current-limiting resistance are connected, be connected between the positive and negative electrode of rectified three-phase circuit after often the opening node and the coil of release is connected of common relay.

Because the utility model adopted such scheme, under normal circumstances, negative phase-sequence filters circuit and is output as zero (perfect condition) or minimum, and deficiency is so that the actuating circuit action.When open phase fault occurring, negative phase-sequence filters circuit big voltage output, make the lumination of light emitting diode of photoelectric relay by single phase rectifier circuit, photoelectric relay often to open node just closed, rectified three-phase circuit is supplied with the coil current of common relay, common relay is often opened the node closure, rectified three-phase circuit is supplied with the release electric current, the release action disconnects air switch, stops motor being powered.The utility model has the following advantages compared with prior art: adopt the basis for estimation of negative phase-sequence signal as the protector action, various situations such as the former and deputy limit phase failure when transformer that is applicable to phase failure when transless directly power to three phase electric machine and passes through the various modes of connection, magnetic structure is powered to three phase electric machine 1..2. consider that negative phase-sequence filters the problem of circuit power consumption, its output current is less, so adopt the initiating terminal of highly sensitive photoelectric relay as actuating circuit, has realized the accurate judgement of actuating signal, has isolated testing circuit and actuating circuit simultaneously.3. adopt novel integrated components such as photoelectric relay, circuit is simple, reliable in action, cost is low, and volume is little, and main circuit board is only about 4.2 * 3.2 * 2cm, can directly be installed on air switch inside, be highly suitable for the transformation and upgrade of existing equipment, can satisfy various users' demand.

Description of drawings:

Below in conjunction with accompanying drawing the utility model is further specified.

Fig. 1 is a circuit block diagram of the present utility model;

Fig. 2 is circuit theory diagrams of the present utility model.

As shown in Figure 1, it comprises that negative phase-sequence filters circuit, single phase rectifier circuit, rectified three-phase circuit and actuating circuit, and actuating circuit is made up of photoelectric relay, common relay and release.As shown in Figure 2, the half-wave rectifying circuit formed by diode D7, adjustable resistance R3, adjustable resistance R4, capacitor C 3 of single phase rectifier circuit.The three-phase bridge rectifier circuit that rectified three-phase circuit is made up of diode D1, D2, D3, D4, D5, D6.Negative phase-sequence filters circuit to be made up of resistance R 1, resistance R 2, capacitor C 1, capacitor C 2, and resistance R 1, capacitor C 1 are connected to the AB two-phase, and resistance R 2, capacitor C 2 are connected to BC two-phase, resistance $R1=\sqrt{3}\×2\mathrm{\πfC}1$ , resistance $R2=\sqrt{3}/3\×2\mathrm{\πfC}2(f=50\mathrm{Hz})$ 。The output Umn two ends of negative phase-sequence filter circuit are by connecting the light-emitting diode of photoelectric relay J1 after the half-wave rectifying circuit rectification, after connecting, the coil of often opening node and common relay J2 of photoelectric relay and current-limiting resistance R5 be connected between the positive and negative electrode of three-phase bridge rectifier circuit, C4 is a filter capacitor, the coil of often opening node and release T1 of common relay J2 is connected in series between the positive and negative electrode of three-phase bridge rectifier circuit, and release T1 connects air switch.

Claims (2)

1, a kind of alternating current machine phase failure protector, it comprises that negative phase-sequence filters circuit, single phase rectifier circuit, rectified three-phase circuit and actuating circuit, it is characterized in that actuating circuit is made up of photoelectric relay, common relay and release; Negative phase-sequence filters the light-emitting diode of the output of circuit by single phase rectifier circuit connection photoelectric relay, be connected between the positive and negative electrode of rectified three-phase circuit after the coil of often opening node and common relay of photoelectric relay and current-limiting resistance are connected, be connected between the positive and negative electrode of rectified three-phase circuit after often the opening node and the coil of release is connected of common relay.

2, alternating current machine phase failure protector according to claim 1 is characterized in that single phase rectifier circuit is that half-wave rectifying circuit, rectified three-phase circuit are three-phase bridge rectifier circuit; Resistance R 1, capacitor C 1 that the negative phase-sequence of being made up of resistance R 1, resistance R 2, capacitor C 1, capacitor C 2 filters circuit are connected to the AB two-phase, and resistance R 2, capacitor C 2 are connected to BC two-phase, resistance $R1=\sqrt{3}\×2\mathrm{\πfC}1$ , resistance $R2=\sqrt{3}/3\×2\mathrm{\πfC}2$ , f=50Hz; The output Umn two ends of negative phase-sequence filter circuit are passed through by diode D7, adjustable resistance R3, adjustable resistance R4, the light-emitting diode that connects photoelectric relay J1 after the half-wave rectifying circuit that capacitor C 3 is formed, after connecting, the coil of often opening node and common relay J2 of photoelectric relay and current-limiting resistance R5 be connected to by diode D1, D2, D3, D4, D5, the three-phase bridge rectifier circuit that D6 forms just, between the negative pole, C4 is a filter capacitor, the coil of often opening node and release T1 of common relay J2 just is being connected in series in three-phase bridge rectifier circuit, between the negative pole, release T1 connects air switch.

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