THE MOST PRECISE LEKAGE CURENT CLAMP TESTER IN THE WORLD
Generally, it is said that the metal oxide surge arresters in high voltage lines should be replaced within 15 years after the start of use under the normal conditions:
Of course, the duration of arresters would be shortened by various causes like as direct surge attack, internal abnormal voltage, vibration & shock to outer pole component, etc. and the regular & adequate inspections are required in order to avoid serious accidents in high voltage distribution networks.
In European standard IEC60099-5 Section 6 “Diagnostic indicators of metal-oxide surge arresters”, the following inspection methods are introduced:
*Fault Indicators *Disconnectors *Surge Counters *Monitoring Spark Gaps Temperature Measurements
*Insulation Resistance Measurements *Leakage Current Measurements (Capacitive, Resistive, Harmonics, etc.)
Among various methods, the leakage current measurements (except for resistive) are only effective, as others are mostly unreliable under the very severe field conditions and some are impracticable due to impossibility of power line off for inspections
ALCL-40/ALCL-40L are adapted to “B1” method of IEC60099-5 Section 6.
ACTUAL MEASURING FIELDS
The most important factor for measuring leakage current is how to detect the real & accurate values (less than 1mA) free from influences of strong magnetic & electric fields in the actual measuring places as above.
Models ALCL-40/ALCL-40L have quite unique & sophisticated CT which enables to measure very low range current with minimum resolution of 0.1μA, defending such outer electric noises.
For example, the comparison list for ordinary & ALCL CT is as followings:
|Influence of Outer Magnetic Fields||Less than 10μA (400A turn/15cm)||Less than 1mA (20A turn/5cm)|
The operation of such field measuring instruments must be rather simple and easier.so that the inspection & maintenance can be made more frequently and the measured data compared correctly, which will lead to find out the problems of surge arresters adequately.
This model ALCL-40 mainly measures very small leakage current of grounding line connected with Arrester, etc. The CT which is applied to this model is hardly affected by external magnetic field and therefore, model ALCL-40 can measure leakage current very accurately in high magnetic and electric field.
1) CT Sensor
|Inside Diameter of CT||:||37mm|
|Structure||:||Apart from Measuring Part|
2) Measuring Part
|Measuring Function||:||Leakage Current, Harmonic Current (Dominant & Third Wave)|
|Measuring Method||:||CT Clamp-on Method|
|Measuring Range||:||0-300μA/3mA/30mA (3range manual)|
|Input Frequency||:||45-60Hz (Dominant Wave Frequency)|
|AC Conversion||:||RMS Detection Method|
|A/D Conversion||:||Double Integration Method|
|Display||:||3200 count max.,LCD|
|Sampling Rate||:||2 times/second|
|Over Indication||:||”OL” on the display|
|Low Battery Indication||:||”B” sign on the display|
|Data Hold Function||:||”DH” sign on the display|
|Auto Power Off||:||Approx.10 minutes after power on|
|Other Function||:||Manually CT open/close (ALCL-40,ALCL-40H)
Motor Drive Switch for CT open/close (ALCL-40L)
Wave Form Signal Output(ALCL-40H)
3) General Specs.
|Power Supply||:||9V Alkaline Battery (6LR61) × 1 (ALCL-40,ALCL-40H)
AA size Alkaline battery×4 (ALCL-40L)
|Operating Circuit Voltage||:||Less than 500V AC|
|Operating Temperature||:||: 0〜40℃, less than 80%RH, w/o condensation|
|Storage Temperature||:||-10〜60℃, less than 70%RH, w/o condensation|
4-1 AC Current
|AC Conversion||:||RMS Detection Method|
|Crest Factor||:||< 3 (0〜50% of the range)
< 2 (50〜100% of the range)
4-2 Harmonic Current(Dominant Current, 3rd Harmonic Current)
|Detection Method||:||Automatic Tuned Filter|
|Min. Dominant Current Input||:||more than 3% of each range|
|Accuracy||:||(1%±5digit)±(AC Current Accuracy) – (Tolerance influenced by adjacent frequency)|
* In case that the harmonic current is more than 4% of the dominant wave
Tolerance influenced by adjacent frequency : 1.5%
5) Dimension & Weight
|ALCL-40 CT Part||:||135(W)×166(H)×61(D)mm, Approx. 1000g|
|ALCL-40H Display Part||:||95(W)×160(H)×334(D)mm, Approx. 260g|
|ALCL-40L||:||160(W)×950(H)×84(D)mm (when retracted rod)
160(W)×2680(H)×84(D)mm (when extended rod)