17.2 The tool is operated intermittently with no load for 24 h of operation at a voltage equal to 1,1 times
rated voltage, and then for 24 h at a supply voltage equal to 0,9 times rated voltage.
The tool may be switched on and off by means of a switch other than that incorporated in the tool.
Each cycle of operation comprises an
″
on
″
period of 100 s and an
″
off
″
period of 20 s, the
″
off
″
periods
being included in the specified operating time.
The operating period for tools for short-time or intermittent operation is equal to the operating time, if this
is limited by the construction of the tool; otherwise, it is in accordance with the prescriptions given in part
2, or with the marking, whichever is the more unfavourable.
During the test, the tool is placed in three different positions, the operating time, at each test voltage, being
approximately 8 h for each position.
During this test, replacement of the carbon brushes is allowed, and the tool is oiled and greased as in
normal use.
If the temperature rise of any part of the tool exceeds the temperature rise determined during the test of
12.1, forced cooling or rest periods are applied, the rest periods being excluded from the specified
operating time.
During these tests, overload protection devices shall not operate.
NOTE The change of position is made to prevent abnormal accumulation of carbon dust in any particular place.
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