◇
39
A
B
C
consequences.
The instrument's ground current detection and judgment circuit response description:
When local line current detection is enabled, the ground current is greater than 0.45mA and the
ground current is over-limit.
When judging the electric shock, the instrument will end the high voltage output within 0.3S and
exit the test state.And display (GFI FAIL)
Note: The instantaneous output current of the instrument may be greater than 30 mA. If it is
indeed an electric shock, it may cause the operator to stun or die.Therefore, it is recommended
to turn on the ground current detection when the product allows.
4.4.8
Current Overrun and Arc Detection (ARC) Function
Current overrun classification: current lower limit, current upper limit, current overrun, arc detection.
Current lower limit judgment (LOW):
Generally used as a test for low-end disconnection,
when the instrument is tested, the device will definitely have a certain leakage current, when the
leakage current of the instrument test is less than the lower limit set current value, it is considered
that the test fails (no device is connected), this function must be turned off if the measured
component itself has a small leakage current. Judgment display (LOW FAIL) when overrun, this
judgment is valid only in test mode, timed sampling, the rate is 100mS each time.
Current upper limit judgment (HIGH):
Most commonly used test current overrun
judgment.When the instrument tests the equipment, the equipment will definitely have a certain
leakage current. When the leakage current of the instrument test is greater than the upper limit set
current value, it is considered that the equipment withstand voltage impedance is insufficient and
the test fails. Judgment display (HI FAIL) when overrun, this judgment is valid only in test mode,
timed sampling, the rate is 100mS each time.
Current limit determination:
Since the current sampling is judged to be slow, when the
insulation collapses, the current changes rapidly, the sampling circuit cannot reflect in time, and
the current peak exceeds the allowable output range of the instrument, which will trigger such
over-limit judgment, Judgment display (SHORT FAIL) when overrun.Since the data cannot be
collected after such current exceeds the limit, the output of the system is: the test result within
100mS before the current exceeds the limit.The current limit is twice the allowable output current
of the instrument (1.5 times the peak value of AC).The fall time is invalid and
this judgment
cannot be shielded.
Arc Detection (ARC):
It is a very practical function for the measurement of coil components, it
tests the local current oscillation caused by the instantaneous discharge of the local circuit in the
high voltage test loop. Due to the superposition on the normal test current, the abrupt time is
short, and the above ordinary current detecting circuit cannot make an appropriate judgment in
response to the current change.The arc detection circuit filters out normal current values and only
processes high speed current pulse changes.Since the low-pass filtering and the size of the arc are
inherently random, this function can only estimate the extent of local sparking.Since the data
cannot be collected after the current exceeds the limit, the output result at this time is the last test
result when it is qualified. Judgment display (ARC FAIL) when overrun. ARC current test is
qualitative analysis, the amount of size and test environment, test line distribution, etc., effect
randomness is very large, pay attention when using.
10
100
1k
10k 100k
Comparison of frequency response of current overrun judgment and arc detection: (See the picture
