
B-65222EN/03 CONFIGURATIONS AND SELECTION 2.SELECTION METHODS
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2.1.5 Amount of Travel when Dynamic Brake is Applied
Because the FANUC Linear Motor is a synchronous motor, a dynamic
brake can be applied by short-circuiting the power wires. When an
emergency stop is used, for example, because of an abnormal
condition, a dynamic brake is put in effect.
When a dynamic brake is applied, the moving object coasts before it
comes to a complete stop. The coasting distance is calculated as
follows:
Coasting distance (m) = VM×(t1+t2)+MT×(A×VM+B×VM
3
)
where
VM: Motor speed (m/s)
t1+t2: Control delay time, usually about 0.05 s
MT: Weight of the moving object (kg)
A and B:
Values specific to each motor model, which are as listed below:
Motor model A B
300D/4 7.90×10
-3
5.99×10
-3
600D/4 3.95×10
-3
3.00×10
-3
900D/4 2.63×10
-3
2.00×10
-3
1500A/4 1.24×10
-3
3.02×10
-4
3000B/2, 3000B/4 5.32v10
-4
1.79×10
-4
6000B/2, 6000B/4 2.66×10
-4
8.87×10
-5
9000B/2, 9000B/4 1.77×10
-4
5.97×10
-5
15000C/2 7.34×10
-5
3.75×10
-5
15000C/3 7.27×10
-5
2.39×10
-5
Calculation example
The following calculation of a coasting distance that occurs when a
dynamic brake is applied assumes the selection conditions used in
Subsections 2.1.1 to 2.1.3.
Coasting distance(m)=
1.5×0.05+334× (1.77×10
-4
×1.5+5.97×10
-5
×1.5
3
) 0.231(m)
NOTE
1 Add the coasting distance calculated as above to the
required length of the magnet plate that is obtained
according to the method described in the following
subsection.
2 When only the dynamic brake is used, the required
sufficient braking distance may not be obtained (the
linear motor may coast longer). In this case, add
auxiliary brake systems such as stoppers or
dampers at the ends of an axis and an external
mechanical brake to protect the machine.