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3.9.3 Over-Temperature
If the internal temperature of the supply is above the safety limitation,
over-temperature protection will be triggered; the supply output will turn off and OT
is displayed. In the meantime, OT and PS in the Questionable Status Register will be
set and keep in this state until they are reset and over-temperature state is removed.
You can’t clear the abnormal latched state until the supply temperature falls to its
normal range.
The Power Supply Calibration
Because various factors may cause the reduction of the power supply’s output
precision after it has been used for a period of time, the user should calibrate the
power supply’s output to make the output return to the previous precision. But it is
suggested that the power should not be calibrated frequently. This section mainly
introduces how to unsecure the power supply and the detailed procedures of manual
calibration.
Calibration Instrument
Multimeter (DVM)
FLUKE 45: measures the DC current
KEITHLEY 2000: measures the DC voltage
Power supply:
CHROMA 61601 AC
power supply
Cautions
●
When the calibration is conducted, the ambient temperature should be within the
range of 25
℃±
2
℃
. All testing instruments and the supply power must be
preheated for 30 minutes before the calibration.
●
As when the FLUKE 45 measures a current as high as 9.5A, the sample resistance
temperature will increase and give rise to a change in resistance value, you should
test the high current as soon as possible.
Calibration Procedures
Press the “Vset” key and the display will show as follows:
Press “secure” key after pressing “2nd” key and you will see the following graph:
