Calibration Procedure; Required Calibration Equipment; Calibration Initialization - Extech Instruments 7470 Operation Manual

11. Calibration Procedure

This instrument has been fully calibrated at the factory in accordance to our published
specifications. It has been calibrated with standards traceable to CNLA. You will find
in this manual a copy of the "Certificate of Calibration". It is recommended that you
have this instrument re-calibrated and a safety check done at least once per year.
EXTECH recommends you use "Calibration Standards" that are CNLA traceable, or
traceable to agencies recognized by CNLA to keep this instrument within published
specifications.
End user metrology standards or practices may vary. These metrology standards
determine the measurement uncertainty ratio of the calibration standards being used.
Calibration adjustments can only be made in the Calibration mode and calibration
checks or verifications can only be made while operating in Test mode.

11.1. Required Calibration Equipment

 0 - 10 kV RMS AC and DC Voltage Divider. Voltage divider must handle 14.14kV
peak.
 7470, 20mA AC Ammeter.
 7473, 10 mA AC Ammeter.
 7472, 10mA DC Ammeter.
 7474, 5mA DC Ammeter.
 7470, 7472, 100K, 20-watt resistor, 1000 volt.
 7472, 7473, 100K, 10-watt resistor, 1000 volt.
 7474, 100K, 2.5-watt resistor, 1000 volt.
 7472,7474 1M, 0.25-watt resistor, 300 volt

11.2. Calibration Initialization

Press and hold the calibration key on the rear panel with a pen, pencil, or small
screwdriver while powering ON the High Withstand Voltage Tester. The High
Withstand Voltage Tester enters calibration mode after the power on sequence is
complete.
The program will automatically enter to the calibration mode and the display screen will
show:
Calibration Mode
 : Forward  : Backward
Use the  (Forward) and  (Backward) keys to move through the calibration menu.
The following instructions follow the sequence scrolling forward through the menu.
11.3. Calibration Procedure
11.3.1. Calibration of Hipot Voltage
The first screen to appear in the Calibration mode is the Voltage calibration display.
The display will show:
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