CN2058497U - Automatic testing device for ratio of transformer - Google Patents

Abstract

The utility model provides an automatic testing device for transformer ratio, relating to equipment for testing a transformer and a mutual inductor. The utility model mainly solves the problems of the small testing range, the complicated and ponderous operation, the need of conversion, etc. of the test of transformer ratio existing in the electrical bridge method and the transformer comparison method in the prior art. The automatic testing device for transformer ratio of the utility model comprises a wire connecting group difference and phase sequence converting circuit, an automatic gear shifting circuit, a wave detector with precise quasi-peak value, a VFCA/D converting circuit with high precision, an 8031 monolithic computer, etc. While in use, the automatic test can be realized according to the needs of users, the automatic conversion is realized, the result is directly displayed by the digit, the large testing range is achieved, and the high precision is achieved. The automatic testing device for transformer ratio is suitable for site operation.

Description

Automatic testing device for ratio of transformer

The utility model relates to the equipment of test transformer and mutual inductor, the tester of specifically a kind of measuring transformer and mutual inductor transformation ratio.

The method to transformer and mutual inductor measuring quantitative change pressure ratio has two kinds in the prior art at present: the one, and bridge method, the one, transformer relative method.The former adopts bridge balance, and as QJ35 type transformer-ratio bridge, measurement range is 1.02～111.12,0.2 grade of precision, and this transformer-ratio bridge is the big transformation ratio of energy measurement not.The latter needs a high-precision heavy transformer, and tap is a lot, and measurement range is big more heavy more, carries extremely inconvenient.More than two kinds of method test durations long, the numerical value of reading also needs to convert according to the wiring group (for example y/ Δ, Δ/y etc.) of transformer, just can draw satisfactory transformation ratio.

The purpose of this utility model is to utilize advanced computer technology, a kind of transformation ratio ATE (automatic test equipment) is provided, this testing apparatus can convert according to wiring group automatically, directly shows transformation ratio and calibration value (being the famous brand value) thereof, the error percentage value of comparing with numeral.Test specification reaches 1～2500,0.2 grade of precision, and can simplify test procedure, and accelerate test speed, and make it light, execute-in-place is easy to carry.Another termination operational amplifier IC ₁, IC ₃(+) input end.The accurate quasi-peak detector 1 and wave detector 2 are by operational amplifier IC ₁, IC ₂, IC ₃, IC ₄And corresponding resistance, electric capacity, diode are formed, with the difference in the accurate quasi-peak detector of routine be in capacitor C ₁, C ₂Two ends increased a parallel resistance R ₁₉The output of these two groups of wave detectors, i.e. IC ₂, IC ₄The output terminal of two operational amplifiers connects voltage/frequency transducer VFC again respectively ₁And VFC ₂Input end E ₁, E ₂2 points, promptly 500 Ω adjust the end of potentiometer Rs, the R ' s of full scale, and the other end of Rs, R ' s connects VFC ₁And VFC ₂The input end of module, VFC ₁And VFC ₂Output terminal F ₁, F ₂The T that connects 8031 single-chip microcomputers respectively ₀, T ₁The input end of two timer conters is to VFC ₁And VFC ₂The pulse of conversion is counted respectively.Capacitor C in the accurate quasi-peak detector 1 and the wave detector 2 ₁, C ₂With resistance R ₁₉Time constant between 0.8～1.5 second.

Transformation ratio auto testing instrument provided by the utility model is compared with analogous instrument, and it is big to have measurement range, the precision height, and function is strong, and speed is fast, and the functional reliability height is in light weight, promptly is fit to fixing the use, also is particularly suitable for carrying on-the-spot test.

Below in conjunction with embodiment further with accompanying drawing and block diagram illustrations principle of work of the present utility model.Accompanying drawing 1 is the utility model signal Processing and high precision VFC type A/D transfer principle figure, and accompanying drawing 2 is these instrument transformation ratio tester theory diagrams.

See figure one, during measurement, the 220V alternating voltage is sent into through relay J O and is measured loop (JO closes during measurement, and measuring end is automatic cutout), and one the tunnel directly send the accurate quasi-peak detector 1, converts DC voltage to, sends into VFC as the high-pressure side measuring voltage ₁Wiring group and phase sequence change-over circuit are sent in another road, and the various wiring groups of tested transformer (three-phase) are switched, and 220V is added to tested transformer high-voltage side, and the alternating voltage of tested step down side enter the fluid drive circuit.Shift circuit guarantees to output to VFC when transformation ratio during in 1～2500 range ₂DC voltage maintain between 0.9～9V, improved measuring accuracy.Through the signal of gear shift, send into accurate quasi-peak value detecting circuit 2.The DC voltage that the high and low pressure side is converted to becomes strict proportional relation with the alternating voltage amplitude of input, these two voltages are added to two groups of identical voltage/frequency transducer VFC respectively ₁, VFC ₂Input end, and be converted into the pulse signal that two class frequencys are directly proportional with the input voltage strictness.Two timer conter T of single-chip microcomputer 8031 ₀, T ₁To its counting, the count value of two counters in the same time is compared respectively, just drawn the value of transformation ratio, and send charactron to show.Dial input setting valve among Fig. 1; The button input command; EPROM is used for depositing working routine, and commander's whole instrument is correctly measured automatically.

One, wiring group and phase sequence commutation circuit

This circuit is made up of two waveres, and the regulation that can press table 1 is voluntarily switched, and the corresponding leading-out terminal of the tested transformer of short circuit.A, B, C are tested transformer high-voltage side three-phase leading-out terminals in the table, and a, b, c are the low-voltage side outlet ends, and this testing apparatus respective terminal is also represented with identical sign.The advantage of this circuit is to resemble whenever changes the switching of all will tabling look-up mutually the QJ35 electric bridge.Table 1 wiring group and phase sequence are switched, the short circuit table

Wiring group y/ Δ Δ/y

Measure phase sequence AB/ab BC/bc CA/ca AB/ab BC/bc CA/ca

Short circuit terminal bc ca ab CA AB BC

Two, fluid drive circuit

By relay J ₁-J ₂, low-pressure side gear shift divider resistance and integrated circuit (IC) ₉, IC ₉' constitute, be divided into 4 grades, by microcomputer automatic control, see figure two for details.

First grade of transformation ratio 1-10, J ₁-J ₃Do not conform to intrinsic standoff ratio 34/1

Second grade of transformation ratio 10-100, J ₁Close intrinsic standoff ratio 3.4/1

Third gear transformation ratio 100-1000, J ₂Close intrinsic standoff ratio 0.34/1

Fourth speed transformation ratio 1000 above J ₃Close intrinsic standoff ratio 0.034/1

Third and fourth grade actual needs amplifies.

Three, the accurate quasi-peak detector

By IC ₁-IC ₄Form, the same with common accurate peak detector basically, just in capacitor C ₂Go up a resistance R in parallel ₁₉So, claim the accurate quasi-peak detector.

Four, high precision VFC type A/D converter

Adopt QD450 or QD452(or other producer's like products) modular VFC type A/D converter, precision is up to 0.02%～0.005%.

Above peak detector and VFC conversion is a symmetry fully, thus full remuneration the fluctuation of power supply and the influence of portion temperature variation, so need not consider the influence of mains voltage variations.

This device has also been considered stable judgement, data filtering, fluid drive and wiring group coefficient program except that general monitoring display program.

Claims (3)

1, a kind of transformation ratio ATE (automatic test equipment) of being made up of 8031 single-chip microcomputers, high precision VFC type A/D change-over circuit, measurement wiring change-over circuit and corresponding software, it is characterized in that: tested transformer high and low pressure is surveyed voltage inserts the accurate quasi-peak detector 1 and wave detector 2 respectively after switching input end A ₁, A ₂2 points are example with wave detector 2, A ₂Point is a resistance R ₁₇An end, R ₁₇Another termination IC ₃(+) input end.The accurate quasi-peak detector 1,2 is by operational amplifier IC ₁, IC ₂, IC ₃, IC ₄And corresponding resistance, electric capacity, diode forms, with the difference of the accurate accurate peak of routine wave detector be capacitor C ₂Two ends increased a parallel resistance R ₁₉The output of these two groups of wave detectors is IC ₂, IC ₄The output terminal of two operational amplifiers is received voltage/frequency transducer VFC again respectively ₁And VFC ₂Input end E ₁, E ₂2 points, promptly 500 Ω adjust the end of potentiometer Rs, the R ' s of full scale, and the other end is received VFC ₁And VFC ₂The input end of module.VFC ₁And VFC ₂Output terminal F ₁, F ₂Receive the T of 8031 single-chip microcomputers respectively ₀, T ₁The input end of two timer conters is to VFC ₁, VFC ₂The pulse of conversion is counted respectively.

2, transformation ratio ATE (automatic test equipment) according to claim 1 is characterized in that the capacitor C in the accurate quasi-peak detector ₂With resistance R ₁₉Time constant between 0.8～1.5 second.

3, transformation ratio ATE (automatic test equipment) according to claim 1 is characterized in that VFC ₁, VFC ₂QD450, QD452 or other same generic module have been selected for use.

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