Operating Instructions – Explosion-Proof AC Motors DR63/eDR63, DVE250/280
53
10
Malfunctions of the motor
Malfunctions
10 Malfunctions
10.1 Malfunctions of the motor
Malfunction Possible cause Remedy
Motor does not start up Supply cable interrupted Check connections, correct if necessary
Fuse blown Replace fuse
Motor protection tripped Check motor protection for correct setting, correct fault if
necessary
Motor protection does not switch, controller
error
Check motor protection control, correct error
Motor only starts with diffi-
culty or does not start at all
Motor designed for delta connection but
used in star connection
Correct the connection
Voltage or frequency differs considerably
from the setpoint, at least when switching
on the motor
Provide better power supply system; check cross section
of supply cable
Motor does not start in star
connection, only in delta
connection
Star connection does not provide sufficient
torque
Switch on directly if delta inrush current is not too great;
else, use a larger motor or a special design (contact
SEW-EURODRIVE)
Contact fault on star/delta switch Correct the fault
Incorrect direction of rotation Motor connected incorrectly Swap two phases
Motor hums and has high
current consumption
Winding defective Send motor to specialist workshop for repair
Rotor rubbing
Fuses blow or motor protec-
tion trips immediately
Short circuit in the cable Eliminate short circuit
Short circuit in the motor Send motor to specialist workshop for repair
Cables connected incorrectly Correct the connection
Ground fault on motor Send motor to specialist workshop for repair
Severe speed loss under
load
Overload Measure the power, use larger motor or reduce load if
necessary
Voltage drops Increase cross section of incoming cable
Motor heats up excessively
(measure temperature)
Overload Measure the power, use larger motor or reduce load if
necessary
Insufficient cooling Correct cooling air supply or clear cooling air passages,
retrofit forced cooling fan if necessary
Ambient temperature too high Observe permitted temperature range
Motor in delta connection instead of star
connection as intended
Correct the connection
Loose contact in supply cable (one phase
missing)
Tighten loose contact
Fuse blown Look for and rectify cause (see above); replace fuse
Line voltage deviates from the rated motor
voltage by more than 5%. A higher voltage
has a particularly unfavorable effect in
motors with a great number of poless since
in these, the no-load current is already
close to the rated current even when the
voltage is normal.
Adjust motor to line voltage
Nominal duty cycle (S1 to S10, DIN 57530)
exceeded, e.g. caused by excessive start-
ing frequency
Adjust the nominal duty cycle of the motor to the required
operating conditions; consult a professional to determine
the proper drive, if necessary
Excessively loud Ball bearing compressed, dirty or damaged Re-align motor, inspect ball bearing (→ chapter "Permit-
ted ball bearing types"), grease if necessary (→ chapter
"Lubricant table for rolling bearings of SEW motors"),
replace
Vibration of rotating parts Rectify cause, possible imbalance
Foreign bodies in cooling air ducts Clean cooling air ducts
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