LABS KVVB User manual

Model KVVB Instructions
© Ohm-Labs, Inc. 2019
Ohm-Labs, Inc. 611 E. Carson St. Pittsburgh, PA 15203-1021 Tel. [phone] www.ohm-labs.com
Instruction Manual
Model KVVB
Compact High Voltage Divider

Model KVVB Instructions
Page 1 of 5
1) Description:
Description:
Ohm-Labs’ model KVVB is a dc high voltage divider used for accurate measurement of high
voltages. A recent design upgrade improved the accuracy and changed to a safety input.
The KVVB consists of precision resistors encapsulated in silicon resin in a diallyl phthalate
housing. Careful internal layout and design minimize leakage and corona effects. All dividers are tested
up to full voltage. The KVVB is equipped with three output binding posts (ground, low and output) and
one ceramic post terminal (input). The input terminal a locking high voltage plug with high voltage cable
terminated in a ring terminal. The output posts are gold plated tellurium copper to reduce thermal emf
errors.
The original Julie Research Labs design KVVB, with threaded post terminals and anti-corona ball
input post, is fully supported and available by special order.
2) Model Selection Guide:
Standard Model KVVB 0-10 kV in = 0-10 V out 1000:1 ratio
Non-Standard Models
KVVB – [A] – [B]
KVVB = KVVB series compact voltage divider
A = Rated input voltage in kilovolts
B = Output voltage at rated input
Examples:
KVVB-10-1 = 10 kV input / 1 V output
KVVB-5-5 = 5 kV input / 5 V output
3) Specifications:
Input Impedance: 5 K/V (50 M for 10 kV model)
Output Impedance: 5 K/V (5 K for 1 V output, 50 K for 10 V output)
Output impedance may be specified to match a customer’s meter
Ratio Accuracy: < 0.01 % through full voltage range
Ratio Temperature Coefficient: < 0.000 5 %/°C (< 5 ppm/°C, 0-45 °C)
Dielectric Test Voltage: >15,000 volts, input terminal to ground plane
Physical: 4.375 x 2.9375 x 2.7 inches including input terminal
11.1 x 7.5 x 7 cm including input terminal
Weight: 12 oz. / 340 g
Environmental: 10-60 °C, 15-85 %RH
Storage: -55 to +85 °C, 0-95 %RH
Warrantee: Two years from date of shipment

Model KVVB Instructions
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4) Operation:
It is assumed that the user is familiar with the safety and cautionary practices required with high
voltage systems and devices. Always exercise extreme caution when working with high voltages.
WARNING: ALWAYS INSURE THAT HIGH VOLTAGE SOURCE IS OFF AND GROUNDED BEFORE
CONNECTING. INJURY OR DEATH CAN RESULT FROM HIGH VOLTAGE.
To use the divider, connect the green Ground binding post to a secure earth ground common
with the high voltage source. Connect the high voltage input lead wire terminated in a #10 ring terminal
to the high voltage source. Connect the Low and Output binding posts of the KVVB to the meter or
measuring system. Note that output Low is at Ground potential. See figure 1.
The KVVB divider may be operated in any position. Four corner mounting holes can be provided
to accept #10 or M4 screws.
To determine the input voltage from the measured output, use the following formula:
Volts Input = (V Output) x (Divider Ratio)
Example (for KVVB-10-1):
Output = 0.775 V
Ratio = 10,000:1
Input = 0.775 x 10,000 = 7,750 Volts
Care should be taken not to exceed the rated input voltage for the KVVB Divider. Note that the
low terminal is internally connected to ground.
Figure 1
HV dc
power
source
Load
Input
Gd Low Out
>10 G voltmeter

Model KVVB Instructions
Page 3 of 5
Any meter or non-potentiometric measurement system will load the output of the KVVB,
affecting its ratio accuracy. To limit the error due to meter loading to less than 0.01 %, the meter
impedance should be greater than 10 G For best accuracy, the loading effect on the KVVB can be
calculated, and a correction can be applied to the measured result. To determine this correction, apply
the below equation (1/X = 1/A + 1/B):
1 / (result) = 1 / (KVVB output impedance) + 1 / (meter input impedance)
Example: (KVVB output 50 K; meter input impedance 10 M):
1 / (result) = 1 / (10,000,000) + 1 / (50,000) = 0.000 020 1
Result = 1/0.000 020 1 = 49,751.24 ohms (= loaded output impedance of KVVB)
The 1,000:1 ratio is based on a resistance ratio of 50 M (total) to 50 K(output). If the loaded
output resistance is 49,751.24 ohms, the actual ratio will be:
50,000,000 / 49,751.24 = 1,005.00 : 1
Measuring 10,000 volts in this example will read on the meter as 9.950 25 volt, or 1/1,005 of the
actual voltage. If using a voltmeter, insure that the input impedance is set to >10 G ohm to minimize
loading errors.
5) Calibration:
Either of two calibration methods may be used. One is comparison against a calibrated high
voltage divider; the other is calibration using a high voltage Wheatstone bridge circuit.
For comparison calibration:
1) Connect the KVVB and a calibrated standard high voltage divider (such as Ohm-Labs HVS) to a
secure ground using ground cables of equal length and gauge.
2) Connect two calibrated voltmeters to the outputs of the standard and the KVVB.
3) Connect the high voltage source to the standard and to the KVVB inputs.
4) Apply a low setting of the high voltage supply to verify operation.
5) Apply high voltage to both units. Allow applied voltage to settle for 15 minutes to allow full
stabilization of the KVVB. Use the ratio of the calibrated standard and the meter readings to
determine the KVVB ratio.
(Standard Divider Output Voltage x Standard Divider Ratio) / KVVB voltage = Ratio

Model KVVB Instructions
Page 4 of 5
To use the high voltage Wheatstone bridge method, use a calibrated high voltage resistance
standard (such as Ohm-Labs HVS), a calibrated decade box and an isolated null detector.
This method is described in NIST Technical Note 1215, “High-Voltage Divider and Resistor
Calibrations,” M. Misakian, Natl. Bur. Stand. (U.S.).
High Voltage Standard KVVB input
Null Detector
KVVB output
Rx (Adjustable) Ground
Figure 2
1) Connect the KVVB and the low side of a calibrated decade resistor (Rx) to a secure ground
using cables of equal length and gauge.
2) Connect the high side of the decade resistor to the low terminal of the high voltage standard
(HVS).
3) Connect an isolated null detector to the high side of the decade resistor and to the KVVB output
terminal.
4) Connect high voltage to the HVS standard and to the input of the KVVB.
5) Apply a low setting of the high voltage supply to verify operation.
6) Apply high voltage to both units. Allow applied voltage to settle for 15 minutes to allow full
stabilization of the KVVB.
7) Adjust the decade resistor for null.
8) Use the value of the standard and the decade box to determine the KVVB ratio.
Example: (HVS = 100.000 megohms)
Voltage Rx Ratio = (Rx + HVS)/Rx
2 kV 100,094 1000.06 : 1
4 kV 100,097 1000.03 : 1
6 kV 100,100 1000.00 : 1
8 kV 100,105 999.95 : 1
10 kV 100,110 999.90 : 1
A limited verification of the KVVB's ratio can be performed by connecting a calibrated voltage
source to the input and comparing it to the KVVB output voltage.
The KVVB may be returned to the manufacturer for calibration. The calibration cycle will depend on
the customer’s requirements. Annual re-calibration is recommended.
High voltage
source