Biddle MEGGER - Page 7

or the other, while cranking at full (slip) speed, until the
pointer stands over the Infinity line.
Low Range Instruments do not have leveling facilities and
Index Adjuster. Some older low range instruments of this
type have variable-voltage hand generators, i.e., there is no
slip clutch. Normal cranking speed is about 120 rpm.
When using multi-voltage sets, make proper setting of voltage
selector switch. See Safety Precautions, page 11.
For use of Guard terminal, see page 32.
2. Heavy-Duty Type—Motor Driven
Motor-driven “Megger” sets are used where a large number
of tests are to be made at one location, and also where the time
duration of the test must be continued for many minutes.
FIGURE 4. Hand-operated and motor-drive
Megger Insulation Testers.
To Operate:
Make proper setting of voltage and selector switches.
Follow directions for hand-driven type, page 4, except that
instead of turning the crank, connect to suitable supply voltage
and run the driving motor.
NOTE: Present motor-driven models may be operated con-
tinuously—24 hours per day if necessary. Older models, with
detachable motors, were for intermittent duty up to 30 minutes
at one time.
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