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TESTING – ELECTRICAL COMPONENTS
8
Work procedure
The electrical function is checked in the following chapter exclusively with a
multimeter.
No checks are made with the machine connected to
the mains!
The only exception is the function check of the earth fault breaker
that is done without the machine or earth fault breaker being dis-
mantled.
Circuit board
The circuit board gives the machine two functions:
– Softstart, which gives a soft start with less current surge.
– Elgard™ is a guard that gives a warning by varying the speed in the event of
overload.
The circuit board in the machine cannot be checked without specialist skills
and special measuring equipment. Here the process of elimination method
must be applied. If the power supply (whole cables and switches) are said to be
intact and the stator and rotor are in working order, the fault must be with
the circuit board which is then replaced.
Earth fault breaker function
The earth fault breaker's principle function is fairly simple. The current that
comes in through the phase conductor must also pass the 0 conductor unless
the current takes other routes, e.g. creeping current that is carried on to the
earth conductor.
The conductors run through a coil and if the same current goes in the
opposite direction, no current is generated in the coil. If the difference is
greater than 10 mA between the phase and 0 conductor, a breaker trips the
current to the machine. Note that the earth conductor has nothing to do with
the earth fault breaker.
Function test
Each time the power plug is connected to the mains supply, the RESET but -
ton must be pressed. A relay connects the current and is held in position as
long as there is mains current, or if the earth fault breaker trips due to a fault.
A signal above the button shows that the current is connected.
The TEST button is used to check that the earth fault breaker is working.
Start the machine and press the TEST button. The earth fault breaker must
trip and the machine must stop.