WARNING: EXTREME CAUTION MUST ALWAYS BE EXERCISED WHEN 
TAKING ANY HIGH VOLTAGE MEASUREMENTS. IT SHOULD BE DONE 
ONLY BY QUALIFIED PERSONNEL WHO ARE TRAINED IN THE SAFETY 
ASPECTS OF WORKING WITH HIGH VOLTAGE.
A sample of the output voltage is available in the REMOTE connector. If it is desired to measure the HV output externally, care must be taken to understand the accuracy of the measurement.
When making a DC measurement, such as when the power supply is holding voltage on a capacitor, any HV probe and DVM combination can be used. The Fluke
The value of the resistor R1 and R2 (Figure 5.3) can be calculated as follows:
V M = | R 2 |
| V O where VO is the High Voltage being measured. | |
R | R | 2 | ||
| 1 |
|
| |
Making a pulsed measurement with an oscilloscope requires a compensated HV probe having a wide bandwidth. Simply connecting a DC probe, through the proper resistance, into a scope yields a slow response only adequate for low rep. rate systems. As with DC probes, the pulsed probe resistor voltage coefficient is a problem. In addition, damage to the resistors can occur during pulsing due to high electric field gradients. Also, stray
capacitance to nearby objects can significantly alter the pulse response. For a
Measurements accurate to better than 0.1% can be achieved using a bias technique. For example, if a 40V signal (40kV divided by 1000) is to be measured accurately, the minus input of the DVM would be biased up 40V. The original signal, with respect to ground, is fed to the plus input of the DVM. The bias can be measured accurately for absolute measurements, or relative measurements read directly as the line or load is varied. In the same manner, an oscilloscope return can be biased for accurate peak measurements during pulsing.
83-493-001 Revision G
5 - 3 | Applications |