Wire Suspension is Unnecessary While Using Specific High Voltage Test Line During Self-excitation Measurement with HCL2840 Type E

HIMALAYAL - SHANGHAI - CHINA

Apply specific high voltage test line (yellow) to CVT self-excitation measurement with HCL2840 type E, test line can be laid on the ground not necessarily suspended. Do not apply the red high voltage line. 

Red high voltage line or black CX line is applied to CVT self-excitation measurement with HCL2840 type C and HCL2840 type D, ensure suspension, otherwise it may cause error in the test outcome. The reason for that is the high voltage core wire and shielding are connected and used as high voltage output, shielding layer thus dysfunctional, extra stray capacitance will be generated if laid on the ground which will cause test error. In consideration that on-site wire suspension can be troublesome, HCL2840 type E is equipped with a specific CVT high voltage line, which is a yellow test line, withstand voltage 3kV, high voltage output through core wire, shield layer grounding, this way stray capacitance from high voltage grounding can be transformed into fixed capacitance. See calibration method as following:     

Take HCL2840 as tangent, connect high voltage end to core wire of the yellow test line, connect Cx end to shielding, rise voltage to 3kV, measure C and tgδ of the specific test line. Input measured C and tgδ to the instrument, deduct C and tgδ of the test line during self-excitation measurement, the outcome represents true value of CVT coupling capacitance (C1, C2).    
The yellow specific test line has been calibrated before delivery of HCL2804 type E, with parameter input to the instrument, no extra modification needed. However, on condition of maintenance and replacement of the test line, recalibration and data input is required.      Note: do not use this specific test line as 10kV high voltage output line, for it will lead to insulating layer breakdown, causing CVT measurement error.