Electrical Safety; Overload Protection - Hilti DD-250 E Mode D'emploi

2. DD-250 E diamond drilling rig
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3. Safety
3.1 Safety precautions on the jobsite
Before beginning work with the drilling
system, read the operating instruc-
tions carefully and ensure that the
safety precautions listed below are
observed.
Please also note that permission to
begin drilling work must be obtained
from the site engineer or other authori-
sed person.
■ Ensure that no electric cables, gas
or water pipes etc. are situated
where holes are to be drilled.
■ Cables, pipes or other supply lines
situated in close proximity to where
holes are to be drilled must be swit-
ched off.

3.2 Electrical safety

The PRCD fault interruptor protects
the operator in case of faults in the
insulation of the motor unit or supply
cord (between the PRCD and the
motor unit). This device also prevents
the machine from restarting of its own
accord when power returns after an
interruption in the power supply. The
earth/ground connection protects the
operator from dangerously high volt-
ages in case of drilling into live cables.
The protective function of the ground
fault interruptor must be checked at
regular intervals in accordance with
regulations issued by national author-
ities (see section 7.17).
Printed: 07.07.2013 | Doc-Nr: PUB / 5069602 / 000 / 00
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■ The drilling work must not have a
negative effect on the structural
design of the building (drilling
through steel reinforcement!).
■ Cordon off areas where drilling
work is taking place, particularly
behind/below walls or ceilings
which are being drilled through.
■ Wear a helmet, safety shoes, gloves
and ear protectors.
■ Tidiness and good organisation on
the jobsite help to prevent acci-
dents.
■ Use only original Hilti parts.
■ Protect the motor unit from water
spray and rain.
1. DD-250 E motor unit
2. DD-C-BU chuck
3. DD-CA-M carriage
4. Handwheel
5. DD-R 100-M rail
6. DD-CP-M stop
7. DD-CO-ML taper
8. DD-SL-SML spindle
9. DD-BCQ-ML baseplate taper
10. DD-EP-ML eccentric pin
11. DD-HML-M holder for water collector
12. DD-WC-ML water collector
13. DD-BA-6 baseplate
14. DD-BW wheel assembly
15. DD-SW-L sealing disc
16. DD-MF-ML fine feed unit
■ For overhead drilling, the water
collector and water removal system
must be in good order and function
correctly.
■ The drilling system must only be
operated with the built-in PRCD
fault interruptor (GB-with isolating
transformer).
■ In order to ensure safe, trouble-free
operation, the drilling system must
be kept clean. (Do not clean using a
jet of water.)
■ Drilling work should only be carried
out by trained personnel who have
received instruction on the use of
the equipment.

3.3 Overload protection

Hilti diamond drilling systems are
equipped with mechanical, electronic,
thermal and overload protection devi-
ces.
Mechanical clutch
Protects the operator, motor and
core bit in case the core bit suddenly
sticks.
Electronic protection
In case of overloading caused by
excessive drilling feed pressure, motor
current is reduced automatically so
that the core bit then only rotates slo-
wly. On reducing feed pressure, cur-
■ When working with the vacuum
baseplate on walls an additional
means of securing the rig must be
employed (see section 7.2).
■ If leakage occurs in the water supp-
ly system, the equipment must be
serviced.
■ Do not touch rotating parts.
rent input returns to normal and the
motor continues to run at full power.
Protection against overheating:
The motor is protected against
overheating by a sensor which auto-
matically reduces current input in case
of sustained overloading and at high
ambient temperatures. The machine
can be operated normally after the
temperature of the motor windings
has dropped to a satisfactory level.
The motor windings can be cooled
more quickly by allowing the motor to
run without load.
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