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WARNING!, failure to observe test connection precautions may result in severe injury or death to the operator. The
display will prompt the user to press the HV enable key as follows:
HIGH VOLTAGE ENABLE
REQUIRED
Once the test connections have been verified, press the HV enable button. After pressing the high voltage enable key the final
prompt is:
PRESS ENTER TO
START TEST
Upon pressing the enter key the 944i will sound a number of warning beeps while flashing the HV enable indicator. If the user
has enabled the auto-ground test feature of the 944i, the unit will automatically check the chassis of the DUT for earth ground
continuity before applying high voltage to the DUT.
........................................................................................
Insulation Resistance (Megaohm) Function
To access the insulation resistance (megaohm) function, press the megaohm key. The following prompt will appear:
MEG OHM TEST
DIRECT AUTOMATIC
For the automatic test mode, press the right cursor arrow and then enter. The next prompt is as follows:
ENTER TEST VOLTAGE
1000 VOLTS
This prompt sets the insulation resistance test voltage. The 1000 VDC shown is the default value. If this is the desired test
voltage, press enter. To select another test voltage, use the number keys to input the desired value and then press enter. The range
of test voltages for the Megaohm function is from a low of 100 VDC to a maximum of 5000 VDC (range is extended down to 10
volts with LVIR option). The next prompt is as follows:
ENTER SLEW RATE
100 VOLTS/SEC
The slew rate prompt allows the test developer to automatically set the ramp rate so that the output voltage linearly increases up to
the test voltage. The slew rate can be set from 1 volt per second to 2000 volts per second. If 100 v/s is the desired ramp rate, then
press enter. If another rate is desire, use the number keys to input a new value and then press enter. The next prompt is as
follows:
ENTER MIN RESISTANCE
1.000 MEGOHMS
The minimum resistance value is a built-in safety feature. Should the load resistance drop below this value the 944i will
automatically stop the test. The default value is 1 megaohm. The lowest allowable minimum resistance value is 100 KΩ. Should
the user care to use a different value, just enter the new value and press the enter key. To change the units from M (mega) to G
(giga) or K (kilo) use the cursor arrows.
ENTER TEST TIME
10 SECONDS
The test time is the amount of time that the 944i will hold the test voltage after it has ramped up to that voltage. Test time is also
referred to as dwell time. During the dwell time the unit continuously monitors insulation resistance. If at any time during either
the ramp or dwell period, the minimum limit is exceeded the test is aborted and the DUT is failed. Use the number keypad to
input the desired test time and the press enter. The next prompt is as follows:
SELECT MODE
RUN ADD CHANNL STORE
The cursor arrows may be used to select any of the desired mode options. Detailed instructions on the add, channel, and store
functions can be located in this chapter. If the user desires to run the test just entered more than one time, it is recommended that
the test be stored. To run the test that has just been set up, press enter while "run" is highlighted.
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