|
EXTRA HIGH ACCURACY
HIGH VOLTAGE DIVIDERS
|
 |
 |
|
High Accuracy VD Series |
High Accuracy Outdoor VD Series |
FOR EXTRA HIGH ACCURACY AND STABILITY:
0.01% DC accuracy types are more limited in resonance free bandwidth than
0.1% types, generally being DC to 1MHz instead of the DC to 5MHz or more
for most 0.1% DC accuracy units. 0.1% DC units have in the order of
20-25PPM per degree C temperature coefficient and less than 0.1PPM/volt
voltage coefficients. Extra high accuracy types have much lower DC
temperature and voltage coefficients, being in the order of 1 to 5 PPM/°C
temperature coefficient (0.0001% to 0.0005% per degree C). 0.01% DC and
0.5% to 3% AC units maybe used without full shielding if proximity rules
are observed, but for higher AC accuracy full shielding maybe used to
obtain accuracies better than 0.5%. Calibration correction charts are
provided for all dividers and probes, increasing the accuracy even more if
the correction factors are applied to readings.
ACCURACY CONSIDERATION:
For highest accuracy in high impedance low input capacitance types,
consideration must be given to induced voltage pick-up in leads, corona,
effective capacitance, and voltage gradient and capacitance shift related
to proximity to ground planes, walls, enclosures, and equipment. Load
resistance, and contact potential in cable connectors and switches must
also be considered for DC. Both load resistance and capacitance in cables
and loads must be considered for AC. The divider should be calibrated with
the specific instrument to be used or at least the accurately simulated
load, and also with accurately simulated proximity to ground planes, walls
and nearby equipment if extreme AC accuracy is required for unshielded or
partially shielded dividers. Fully shielded dividers for AC are available
but are much larger and heavier. Absolute maximum accuracy is usually
centered around 2/3 to 3/4 of maximum DC or PK AC voltage rating unless
otherwise required. Certified calibration charts are supplied for
approximately 10% to 20% steps from 10% to 100% rated PK operating
voltage. |
