AlphaLab Electrostatic Bias Voltage Monitor Instructions

This monitor measures and displays the voltage of a high-voltage supply (with respect to the negative of the 24 V supply). The voltage is displayed in kilovolts, with polarity indication. Maximum range is +/- 19.999 kV, in steps of 0.001 kV (1 volt). Accuracy is +/- 2% of the reading. In addition, a relay will close and a pulsing alarm will sound if the measured high voltage drops below a level that you set.

To use the monitor, connect 24 VDC where indicated on the terminal block. Any voltage between 13 and 29 VDC will work. Accidental 24 V reverse connection will not harm the monitor, but it will not operate until connected correctly. Current consumption is 50 ma quiescent, and 160 ma at maximum while alarm is sounding.

Connect the gray cylinder. This contains a 100 Megohm resistor, which reduces the high voltage so it can be measured. It works equally well if either side of the cylinder is connected to the high voltage, but for safety, the long wire that is permanently attached should be connected to “HV probe” on the terminal block. Then use the included short cable (banana-to-alligator cable) to connect the cylinder to your high voltage supply (the same high voltage that is connected to the part to be coated). As now connected, the long wire is entirely at low voltage. (Whenever the high voltage is connected, keep the long wire connected to “HV Probe” on the terminal block and maintain a path to ground by keeping at least the negative of the 24V supply connected to the block. This will prevent low-power sparks from coming out of the long wire. These sparks could damage other electronic devices nearby.)

Connect the alarm if needed. You may want to use a switch in series to prevent unnecessary alarm sound when if your high voltage is ever off at the same time as your 24 V supply is on. Another version of this monitor is available that mutes the alarm if the high voltage is under 50 V. The relay contacts are both isolated, and will be closed only when the high voltage is below your set alarm level.

To set the alarm level, press and hold “Push for Alarm Level” and rotate the “Alarm Level” to the desired minimum voltage, which will be displayed. (It will remain at this level until you rotate it again.) When set for example at “4.900”, the monitor will not sound the alarm and the relay will be open if the voltage is either + 4910 or - 4910 volts or higher. However, it will sound the alarm and close the relay if the voltage is either + 4890 or - 4890 volts or lower.