4. Wide range of application, any power plant, transformer substation,
colliery, chemical plant and others power supply departments.
5. Easy to carry, the signal receiver equipped with battery, do not need
external power source.
6. DC system do not need power off when searching the ground point, do
not affect the normal work of the system.
7. Strong anti-jamming ability, without the effects by system distributed
capacitance.
8. Intelligent charge management, shorten the charging time, lengthen the
battery life.
II. Principle
This device applies to detect the accurate ground point position of power
plant, transformer substation DC system. It uses new method: waveform
analysis, its features and advantages: high measurement sensitivity, detection
under no power interruption, no effect to system normal work, strong
anti-jamming ability, safe and reliable.
Waveform analysis : inject one special cyclical voltage signal between DC
bus bar and ground, detect the current of each branch using caliper probe,
analyze and calculate phase and phase difference of current signal
fundamental wave and harmonic wave, and then judge if there was ground
fault or ground fault contact.
This device is composed by signal generator, signal receiver and signal
sampler (caliper). These three parts should be matched use when detect the
DC ground fault.
This signal generator adopts new digital technique instead of using
traditional LC or RC oscillation circuit, it with the features of stable signal. This
signal generator is composed by single chip, A/D converting circuit, signal
amplifying filter circuit, power amplifying & blocking circuit, output feedback
and protection, its principle as follow:
