MEGABRAS MD-5060x Guia Del Usuario página 12

period, the operator must press the DAI key to read the absorption index
value on the display. If this key is pressed before the 1-minute period has
elapsed, the display will show DAI = - - -. The Dielectric Absorption Index is
the ratio between the insulation resistance value measured after 60 sec-
onds and the value measured after 30 seconds. This value is useful to
determine whether it is necessary to perform preventive and predictive
maintenance on the coils (transformers, engines and motors, generators,
etc.).
Polarization index (PI)
This key makes it possible to visualize the Polarization Index value on the
display. For this type of tests, the megohmmeter must be connected and
apply voltage to the sample for 10 min. After this period, the operator must
press the PI key to display the PI value on the megohmmeter display. If the
key is pressed before the 10-min period has elapsed, the display will show
PI= - - -. If it is pressed after the 10-min period, it will indicate the PI value.
The polarization index is the ratio between the insulation resistance value
measured after 10 min and the value measured after 1 min. This index is
useful to determine whether it is necessary to perform preventive and pre-
dictive Maintenance in order to detect any insulation resistance wear and
tear due to the excess of dust, dirt, grease, or else the action of chemical or
physical agents, etc.
SVT – Step Voltage Test
After selecting the SVT function with the function key, the operator must
select the test maximum voltage with the ±500 V keys. In this function, the
equipment allows the selection of maximum voltages only from 500 V up to
5000 V steps. If the operator selects a halfway voltage between two 500 V
steps by using the ±100 key, the equipment will carry out the test from the
500 V up to reaching an equal voltage value or a value that is straight be-
low the 500 multiple value. During the first minute the generated test volt-
age is of 500 V. This voltage is incremented in 500 V steps until it reaches
R
DAI =
60 seconds
R
30 seconds
R
PI =
10 minutes
R
1 minute
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