Brake Malfunctions - SEW-Eurodrive DR2..71/BE Series Operating Instructions Manual

9.2

Brake malfunctions

Fault Possible cause
Brake does not re- Incorrect voltage on brake control
lease unit
Brake control unit failed
Maximum permitted working air
gap exceeded because brake lining
worn down.
Voltage drop along supply cable >
10%
Inadequate cooling, brake over-
heating
Brake coil has interturn short circuit
or a short circuit to frame
Rectifier defective
Brake does not Working air gap not correct
brake
Brake lining worn
Incorrect braking torque
Brake does not Working air gap so large that set-
brake ting nuts for the manual release
come into contact
Manual brake release device not
set correctly
Brake locked by manual brake re-
lease HF
Brake is applied Brake is switched only on AC
with time lag voltage side
Measure
Apply the correct voltage; brake voltage specified
on the nameplate.
Renew brake control, check resistors and isolation
of the brake coils.
Check switchgear, replace if necessary.
Measure and set working air gap.
If the brake disk is too thin, replace the brake disk.
Provide correct connection voltage: brake voltage
specifications on the nameplate. Check the cross
section of the brake supply cable, increase cross
section if necessary.
Provide for cooling air supply or clear cooling air
passages, check air filter, clean or replace if ne-
cessary. Replace type BG brake rectifier with type
BGE.
Check resistors and isolation of the brake coils;
Replace complete brake and brake control (spe-
cialist workshop);
Check switchgear, replace if necessary.
Replace rectifier and brake coil; it may be more
economical to replace the complete brake.
Measure and set working air gap.
If the brake disk is too thin, replace the brake disk.
Replace entire brake lining carrier.
Check the dimensioning and, if necessary,
change braking torque by type and number of
brake springs, or by selecting a different brake.
Set the working air gap.
Set the setting nuts for the manual release cor-
rectly.
Loosen the set screw, remove if needed.
Switch both the DC and AC circuits (e.g. by retro-
fitting a SR current relay to BSR or a UR voltage
relay to BUR);
Observe wiring diagram.
Operating Instructions – AC Motors
Malfunctions
9
Brake malfunctions
229