Analysis and Maintenance of ZQZ-CII Automatic Station Power Supply Charging Circuit Diagram

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One-piece inductor

introduction

ZQZ-CII type automatic station power supply charging circuit is an auxiliary equipment of ZQZ-CII type automatic station power supply. When the mains power is not normal, it is powered by battery and automatically converted. There is a battery in the backup power supply with a capacity of 8Ah/12V, which ensures that the data collector and sensor work for 3 days in the event of power failure. It ensures the normal and reliable data acquisition of the collector, and has the advantages of simple design, rapid response, low cost, reliable use and simple maintenance. It is widely used in ZQZ-CII automatic weather station.

1 circuit principle

ZQZ-CII type automatic station power charging circuit is shown as in Fig. 1.

1.1 Mains input circuit

The mains input circuit (automatic station power supply and charging circuit sharing) is composed of power supply lightning arrester P1, P2 band pass filter Z and isolation transformer T1. The role of each part of the role: power supply lightning protection device is a low-voltage power supply protection device, when the mains due to lightning strikes or other factors to produce high pulse voltage, the power supply lightning arrester can release the circuit in the shortest possible time due to induced lightning strikes A large amount of pulse energy is applied to the safety ground to protect the user equipment on the circuit; the band pass filter is used to suppress the interference of the power grid from entering the collector through the power supply, and the second is to prevent the higher harmonics and low harmonics on the circuit. Wave pollution grid; the main function of the isolation transformer is to isolate the power supply [3], cut off the coupling path and transmission channel of the electromagnetic interference source, the primary secondary transformation ratio of the transformer is equal to 1, the mains ground and the circuit ground are separated, thus Effectively prevent the occurrence of electric shock accidents and protect personal safety.

1.2 Transformer, rectifier, filter circuit

The transformer, rectification and filtering circuit is composed of T2, D1~D4 and C1. The full-bridge rectifier consisting of 14V transformer T2 and D1~D4 is connected to 220V AC. After C1 filtering, it outputs about 15V DC power to supply power to LM317.

1.3 battery charging circuit

The battery charging circuit is composed of a three-terminal adjustable voltage regulator integrated block LM317, an output voltage regulating circuit (R1, R2, RP1), a protection diode D5, D6 and the like. After C5 filtering, the DC output of about 13.8V is output to the LM317. After the internal regulation of the LM317 and C5 filtering, the DC voltage of 13.8V is output to charge the battery. R1, R2, RP1 constitute the output voltage regulation circuit, the output voltage value can be changed by RP1, D5 is the protection diode, the input short circuit is prevented and the voltage regulator integrated block LM317 is damaged. The D6 is used to prevent the output terminal of the voltage regulator integrated block LM317 from being short-circuited. Damage to the LM317, C2, C4 to suppress the ripple voltage, D7 is an isolation diode to prevent the battery voltage from being fed back to the front-end voltage regulator circuit after the mains power failure, damaging the front-end circuit. R3 is a current limiting resistor that prevents the load from overcurrent protection of the regulator block [1, 2].

2 troubleshooting methods for common faults

2.1 Plug into the mains burning fuse

The plug is inserted into the mains burning fuse, and the possible causes of the fault are: the lightning arrester P1 or P2 is short-circuited; the band-pass filter Z is short-circuited; in the full-wave rectifier bridge, the diodes are short-circuited by D1 to D4; the filter capacitor C1 Short circuit or leakage current is too large. Maintenance example: (1) plug into the mains burning fuse, after checking the full-wave rectifier bridge D2 breakdown short circuit, change the instrument to return to normal; (2) bandpass filter Z short circuit, the instrument returns to normal after replacement.

2.2 There is no charging voltage at both ends of the battery

There is no charging voltage at both ends of the battery. The causes of the fault are: the three-terminal adjustable voltage regulator integrated block LM317 is damaged; the R3 is blown; the D6 is short-circuited; the maintenance example: disconnect the battery terminal, and measure the terminal of the battery with a multimeter. Voltage output, measure the voltage across the capacitor C5, take off the isolation diode D7 measurement, D7 open circuit is broken, replace the D7 output voltage is normal.

2.3 Charging circuit load capacity decreased

The charging circuit has a reduced load capacity, resulting in insufficient battery charging and a short battery discharge time after power failure. It is important to check whether the capacity of the filter capacitor C1 becomes small or the leakage current is too large; whether the rectification characteristics of the diode in the full-wave rectifier bridge deteriorate, whether the individual diodes are in an open circuit damage state; whether the performance of the LM317 is degraded. Maintenance example: After the power failure, the battery discharge time of the city is significantly shorter than that of the original discharge. After replacing the battery, the fault remains. Turn on the power supply case and check that the rectifier diode D3 has been opened in the full-wave rectifier bridge. After the replacement, the charging circuit returns to normal. .

2.4 Charging circuit output voltage fluctuates

The output voltage of the charging circuit is high and low, and the adjustable potentiometer RP1 is mainly checked. Generally, the internal contact is not good after the potentiometer is used for a long time. After the adjustable potentiometer is replaced, the output voltage is normal.

3 Conclusion

Through the analysis of the circuit principle, function, fault location of common fault phenomena and specific troubleshooting methods of the ZQZ-CII automatic station power supply charging circuit. The staff engaged in automatic station maintenance can quickly and accurately eliminate faults during maintenance. This ensures that the automatic station collector operates normally and reliably.