Manual
BHK-MG 1/2 OPR 121313 4-1
SECTION 4 - CALIBRATION
4.1 GENERAL
This section contains the calibration instructions for the Power Supply. It is recommended that
the user be familiar with Local Mode operation (PAR.3.2) before calibrating the unit.
A full calibration consists of a voltage calibration and a current calibration. Voltage calibration
consists of a zero and a full scale calibration, current calibration consists of a zero, full scale and
10% of full scale calibration. (Refer to PAR. 4.3 for more information.)
There are three ways to perform the calibration: 1) locally using the front panel keys (PAR. 4.4),
2) remotely sending commands through the GPIB bus, or 3) remotely using the graphical inter-
face supplied with the instrument driver available at www.kepcopower.com/drivers.htm (PAR.
4.5). This VISA compliant driver works with many GPIB cards from suppliers like National Instru-
ments and Hewlett-Packard. These three calibration methods cannot be combined.
In order to enter the calibration mode the correct calibration access code (password) must be
entered. If the password has been forgotten, call the factory. During the calibration, new calibra-
tion data is computed which is then stored in the nonvolatile memory.
4.2 EQUIPMENT REQUIRED
The following equipment is required to calibrate the BHK-MG 40W Power Supply.
• Digital Voltmeter (DVM) with 6 digits resolution an at least 0.002% accuracy for d-c mea-
surements.
• Precision Shunt Resistor (with a tolerance of 0.01%, power rating of at least 10 times
larger than the maximum stress, and a temperature coefficient equal to or better than 20
ppm per degree C). During the calibration procedure the LCD displays the minimum
requirements for the shunt resistor. However, to avoid problems due to drift caused by
heat dissipation, Kepco recommends the following:
– BHK 300-130MG: 7.69 Ohms, 0.01%, 25W
– BHK 500-80MG: 12.5 Ohm, 0.01%, 10W
– BHK 1000-40MG: 25 Ohm, 0.01%, 10W
– BHK 2000-20MG: 50 Ohm, 0.01%, 5W
NOTE: • Because the voltage measured will be used as reference for calibration, the DVM
used must be accurately calibrated prior to calibrating the BHK-MG 40W Power
Supply.
• Proper cooling of the external precision shunt resistor ensures the accuracy of the
calibration.
4.3 CALIBRATION DESCRIPTION
During voltage calibration, the voltage, overvoltage and voltage readback are calibrated and
during current calibration the current, overcurrent and current readback are calibrated. The nor-
mal procedure is to calibrate voltage first and then current. However, you do not have to do a
complete calibration each time. If required, you may calibrate only the voltage or the current and