About the performance characteristics and technical indicators of triple frequency induction voltage test device First, product technical characteristics:
The push-pull amplification variable-frequency power supply is a linear matrix amplification network composed of low-frequency high-power transistors and works in a linear amplification area to obtain a standard sinusoidal waveform that is consistent with the signal source. Because there is no circuit inside the switch state, therefore, No serious interference signal, the output is a pure sine wave, which is suitable as a power supply for partial discharge test, also suitable as a resonant test power supply, can increase the loop Q value by 20%.
The general frequency conversion test power supply is a square-wave variable-frequency power supply constructed using the pulse width modulation principle. Since it operates in the switch state, the output is a square wave or a quasi-sine wave (a sine wave composed of multiple square waves), and there are a large number of high-order harmonics. Wave and high-frequency interference, due to the wide interference bandwidth and radio frequency interference is difficult to use filters to eliminate interference, using it as a partial discharge test power is difficult to control the partial discharge below 50pC. And because the output of the square wave variable frequency power supply formed by the pulse width modulation principle is a quasi-sine wave (a sine wave composed of a plurality of square waves), there are many glitches, which affect the turn-to-turn insulation of the PT during the PT induction withstand voltage test. Users are not recommended to use square wave variable frequency power supply for PT induction withstand voltage and partial discharge test. The square wave variable frequency power supply is suitable as a test power supply for a resonant test. (compared with square wave power supply)
Push-pull amplification test frequency conversion power supply can also be used in 50Hz power transformer no-load loss test and substation ground network ground potential distribution and grounding impedance measurement of high-current variable-frequency power supply, can be used as a pure sine wave FM, pressure regulator Device. A multi-purpose machine, with a very high cost performance.
Technical and technological measures to improve reliability of push-pull amplification test frequency conversion power supply: (Core components selection)
1, push-pull amplification test frequency conversion power amplifier design leave a larger margin, the current selection of Japan Sanyo's 250-watt 2SC3997 high-power transistor, at 105 °C constant temperature, apply 2 times the working voltage and 1.5 times The working current is screened, and the reliability is greatly improved. It can withstand the short circuit of the output and the short-term overload capacity is 120%.
2. The amplification of the power amplifier triode is strictly screened, the error is within 2%, and the current sharing circuit is provided to ensure that the deviation of the working current of the triode with different magnifications does not exceed 6%;
3, reliable welding process, 100% no-welding and short circuit, open circuit. Thousands of transistors are only equivalent to four high-power transistors on the premise of reliable connection.
4. The new design has improved the heat dissipation effect and the heat dissipation effect has been greatly improved. The temperature difference between inlet and outlet is less than 20°C, making the power amplifier tube work safer.
5, the main circuit protection to cancel the resistance sampling, using a dedicated sensor, the trigger time is less than 1 microsecond, the output fault, the main loop can be closed within 20 microseconds, close the push signal within 2 microseconds to ensure that the high power is not damaged tube. (Rapid protection response)
6. Due to the poor temperature performance of the high-power tube, when the power output is larger, the temperature rise increases, the amplification of the transistor increases, and the output voltage drifts. The tester constantly adjusts the output voltage. This problem cannot be solved in the early stage. . The software feedback system for stabilizing the output voltage is now controlled by a single-chip microcomputer. The output voltage negative feedback system is sampled by a Hall element voltage sensor, and the voltage drift due to temperature rise is constantly corrected to ensure that the output voltage is constant without being affected by temperature rise.
7. The signal source of the variable-frequency power supply for the push-pull amplification test is generated by a dedicated chip and controlled by a single-chip microcomputer. The output frequency is stable and the adjustment is finer. All data is displayed on a large screen LCD screen.
8. All chips used in the equipment are imported chips, among which the main components are as follows: 1 High-power power tube (Japan Sanyo 3997); 2 Electrolytic capacitor (Japan Hitachi); 3 AC circuit breaker contactor (Schneider, Germany) 4 Terminals (Phoenix) 5 control box chassis (Germany Rittal); 6 illuminated buttons (Switzerland DECA) using professional mass production, has a perfect process guarantee system to ensure delivery.
Second, product use conditions:
· Ambient temperature: -15 ~ 45 °C (When the environment changes 10 °C, the instrument error does not change the amount of basic error 1/2)
Relative humidity: When the ambient air temperature is 25°C, the relative humidity is ≤95%
·Power supply: 380V±10%, 50Hz
·Altitude: ≤1500m
Third, the main technical parameters of the power supply: 380V ± 10%, 50Hz
Output voltage: single-phase sine wave 0 ~ 350V continuously adjustable output current: 0 ~ 42.8A
Rated output capacity: 15kW
Output frequency: 20 ~ 400Hz continuously adjustable output frequency fineness: 0.1Hz
Output frequency instability: ≤0.01Hz
The output waveform is sine wave: waveform distortion rate ≤ 1%
Test time setting range: 0 to 99 minutes, precision 0.1 second Insulation level: 1.1 times rated voltage withstand voltage 1min
Continuous operating time and temperature rise: Under rated power, sustainable operation for 60 minutes, outlet temperature rise ≤60K
Cooling method: forced air cooling noise level: ≤60dB
The frequency conversion power supply has a built-in filter to suppress the partial discharge interference from the power supply side