Single-Phase Relay Protection Tester
The relay protection testing instrument is divided into two circuits: the main circuit and the auxiliary circuit. The main circuit is adjusted by a large knob, while the auxiliary circuit is adjusted by a small knob. The main circuit controls the various output quantities through the "Output Selection" button switch on the panel, and each time a different output is switched, the digital voltage/current meter on the instrument can automatically monitor its output value. The auxiliary circuit can be directly adjusted and output through the output switch control, and measurement does not require an external multimeter; it is displayed through the instrument's display.
Principle of the Main Circuit of the Relay Protection Testing Instrument
The input AC220V power supply passes through the fuse and enters the input terminal of the double carbon brush voltage regulator T1 through the output control relay K1. The electricity adjusted by the large knob of T1 enters the isolation transformer T2 (also serving as a current booster). The current booster has three tap outputs: one tap is AC0-250V output with a rated current of 3A; the output voltage of this tap can be rectified and filtered to produce a 0-350V DC voltage; the second tap is 15V (10A), and this tap outputs 0-10A AC current through a sensor and relay control, 0-500mA AC current through a resistor, and can be converted to output 0-10A or 0-500mA DC current through relay switching; the third tap is the 10V (100A) high-current terminal, which passes through the primary side of the sensor and directly outputs 100A current. This circuit has strong load capacity, but the output is slightly overloaded and cannot be in a high-current state for a long time. Thermal Relay Calibrator
The auxiliary circuit of the relay protection testing instrument is the same as the main circuit. The AC220V power supply enters the double carbon brush voltage regulator T1 through the fuse, and the voltage adjusted by the small knob can be directly adjusted through the isolation transformer T4 to output 0-20V or 0-250V AC voltage or 0-350V DC voltage. The rated current of this circuit is 1A. Press the "Output Control" switch of the auxiliary circuit and adjust the small knob to output.
Measurement Circuit
The main circuit output quantities adjusted by the large knob, AC "0-250V", "0-500mA", "0-10A", "0-100A", and DC "0-350V", "0-500mA", "0-10A", are converted through relays on the circuit board inside the device. Each time a gear is switched, the corresponding output quantity can be monitored. Among them, the "0-500mA" gear is included in the "0-10A" gear. When in use, the "0-500mA" monitoring is right below the "0-10A" position.
Time Measurement
The device is equipped with a built-in 6-digit digital stopwatch, which can be started internally or externally. When started internally, press the "Output Control" switch to start the stopwatch, and short-circuit the stop terminal on the panel to stop it. The stopwatch has a separate power switch and can be turned off when not in use.
Audible and Visual Indication
The circuit device is equipped with an audible and visual indication circuit. When the contacts of the relay under test operate, the contacts can be connected to the audible and visual indication jack of the test box, and the test box will emit an alarm sound or light up to indicate the contact operation of the relay.
