Lenze MGXQK DC motors - Manual (Page 12)

12
6. Commissioning and operation
n Do not operate in hazardous areas!
n
Depending on the operating state, the
surface temperature can exceed 90 5C.
Keep cooling times!
Do not touch motor surface if drives are in
operation!
Provide protection against skin contact if
necessary!
n Fire risk! Do not spray or clean drives with
inflammable detergents or solvents!
n Avoid overheat!
Deposits on drives obstruct the required
heat dissipation and must be removed in
intervals.
6.1 Checking before commissioning
n
Check the drive only when no voltage is
applied!
Check the following items before
¯
the first commissioning
¯
commissioning after a long period
standstill
¯ commissioning after maintenance of the
motor
-- firm connection of the screws of the
mechanical and electrical parts
-- completeness of the set of carbon
brushes
-- easy sliding of the carbon brushes in
the brush holders
-- contact of all brush holder springs on
the carbons
-- if an oxyde layer has deposited on the
collector surface:
Grind using a collector hand finishing
stick or a corundum brick. Never use
solvents for cleaning.
-- brush in ”neutral position” (coloured
mark at the brush yoke and at the
endshield must coincide)
-- sufficient insulation resistance (see
chapter 6.1.1)
-- unimpeded inlet and outlet of cooling air
-- efficiency of the protections against
overheat (checking the thermal snesors)
-- direction of rotation of the separate
blower
6.1.1 Measuring the insulation resistance
¯
To measure the insulation resistance,
disconnect the connecting cables.
Earth the winding parts which are not to be
checked and the thermal sensor.
¯ Check the following insulation resistances:
-- across rotor and stator windings
-- across brush rulers with lifted brushes
and across earth
¯ Test voltage:
highest rated motor voltage or 500 V
¯
Test temperature:
test motor housing for ambient temperature
Minimum insulation resistances:
¯
New motor:
The insulation resistance in kW must be at
least as high as the highest rated motor
voltage. Example:
U
A
= 460 V; U
f
= 360 V
⇒insulation resistance R
I
≥ 460 kW
When the resistance is smaller, dry the
motor before commissioning.
¯
Recommissioning:
The insulation resistance of a motor which
had been in operation already, must be at
least 50 kW.
When the resistance is smaller, clean the
windings and the area of the collector and
brushes. After a long period of standstill,
an additional drying may be necessary.
Possible procedure for drying:
1. Use a blower to blow dry, warm air of 80 5C
from the B--side through the motor.
If possible, slowly rotate the rotor.
2. Allow housing to cool to ambient
temperature
3. Measure insulation resistance
4. Repeat drying procedure until the
insulation resistance has obtained the
required value.
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