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Supply
"ELCEN"
Brake motors are normally supplied with D.C. fail safe brakes, also
known as normally ON brake. The motor is braked (Locked) when power
is not applied i.e. de-energized to brake. This ensures real fail safe
braking. The constructrion is quite robust and requires very limited
maintenance. With wearing of liners on the rotor of brake, the air-gap
has cna be easily adjusted. If necessary, the rotor can be easily adjusted.
If necessary, the rotor can be easily replaced completely as well. The
brake is mounted on end covers on non-driving end of the motor. It comes
with a Manual release lever.
Selection
Depending upon the application, the service factor of the brake has
to be selected for proper braking.
Types
of Load |
Safety
Factor |
Low
mass, uniform loading, non-intermittent operation |
2 |
Low
mass, light shock load with intermittent operation |
2.5 |
| Medium mass, light
shock load with intermittent operation |
3 |
| Heavy mass, light
shock load with intermittent operation |
3 |
| Overhauling Loads |
3.5 |
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Service
factors for guidelines are mentioned in the selection table.
How ever while selecting the service factpr, other criteria like mounting
positions, type of transmission and reductions should also be considered
as well.
Supply
Unless
otherwise specified, brake voltages are 190 V.D.C., with a rectifier
of 415V A.C. dual phase input and 190VD.C. output, duly fitted
in the terminal box of the motor. For quicker releasing action,
96V D.C. brakes can be used with the same rectifier but with an
input supply of 230V A.C. Brakes with 24V, 48V D.C. can be supplied
but without rectifier. For these supply voltage of brake, inbuilt
rectifier is not available, hence the brake has to energized and
de-energized separately.
Switching
Motors
are connecteed with AC switching as standard. For faster action
and reduction of the delay in operation, DC switching can be used.
Care must be taken with DC switching as it generates heavy sparking,
which can lead to shorting of switching contacts and ultimately
leads to failure of contact braking. Suitable imoversa; shock
suppressors and capacitors can be used (not in the scope of "ELCEN")
Air-Gap
Adjustment
The
braking torque and time is related to air gap between the rotor
and stator. It is recommended to verify and if required to adjust
the air-gap periodically for consistent performance. The brake
is mounted on the end cover with three to six ellen bolts "L".
Near the outer periphery of the brake, these ellen bolts "L"
pass through Hollow hex bolts "H" which are in the opposite
direction of the ellen bolts "L". There is an axially
moving plate "M" between the armature and brake coil
housing. The air gap between this moving plate "M" and
brake coil housing has to be maintained. It can be measured iwth
a filler gauge or another suitable measuring system. To change
the air gap, loosen all the ellen bolts "L" and unscrew
all the hollow hex bolts "H" slightly to increase air
gap and tighten them to reduce air gap. Tighten the leen bolts
"L" and measure the air gap near these olts, and if
required, adjst the air gap again to achieve specified air gap.
The air gap is recommended in the table below.
| Brake
Size |
6 |
8 |
10 |
12 |
14 |
16 |
18 |
20 |
25 |
| Air-Gap
in mm |
0.2 |
0.2 |
0.2 |
0.3 |
0.3 |
0.3 |
0.4 |
0.4 |
0.5 |
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