159
Step
Item
Calculation or procedure
1
Choose the duty cycle T
With user
‟s application to decide the repeat operation cycle.
2
Set motor speed
Panel operation to read/write this value.
3
Set load to motor inertia ratio N
Panel operation to read/write this value.(PA02=0002h)
4
Compute the Es
Refer to the previous table
or calculation
Es = J × Wr
2
/ 182
5
Compute the Ec
Refer to the previous table
6
Compute the P
BR
2 x ((N+1) x E
S
-E
C
)/T
Example 1
The drive capacity is 400W, duty cycle T is 0.5 second, revolution speed is 3000 rpm, load to motor
inertia ratio is 3, then the necessary power of brake resistor = 2 x ((7 + 1) x 1.33 -19.78 ) / 0.5 = 36.56W.
Users need to apply an external resistor which its power should be greater than 37W.
Note
: Due to 3000rpm is the rate speed of 400W servo drive; we could find the Es on the previous table
is 1.33.
Example 2
The drive capacity is 2KW, duty cycle T is 1 second, revolution speed is 1000 rpm, load to motor inertia
ratio is 20. Since the revolution speed 1000rpm is less than the rated speed (2000rpm), we need to
compute E
S
, E
S
=32.48 x 10
-4
x 1000
2
/182 = 17.8, then the necessary power of brake resistor = 2 x ((20
+ 1) x 17.8 - 81.5 ) /1 = 584. These are more than the capacity (50W) of 2KW servo drive
‟s built-in
brake resistor. So, a 1000W brake resistor is recommended.
Generally, if the load inertia ratio is small (N<=5), the capacity is sufficient. If the brake resistor capacity
is too small, the heat
accumulated
is growing easily and the temperature of brake resistor rises soon.
When the temperature is higher than a certain value, the brake resistor w ill be burn out.
(b) With external load
When the external load torque is greater than motor torque, it makes the servo motor output
torque direction is opposite to the rotary direction of servo motor. In this case, the external energy is
delivered to the servo drive through the servo motor. The following figure is an example that the motor
runs in CCW rotation at constant speed when a sudden external load torque change.
Summary of Contents for SDE Series
Page 13: ...5 1 6 Function block diagram ...
Page 26: ...18 3 3 3 CN1 pin name list ...
Page 223: ...215 SME L040 SME L075 SME L100 SME L150 ...
Page 224: ...216 SME L200 SME L300 SME M100 SME M150 Continuous running range ...
Page 227: ...219 ...
Page 231: ...223 4 Wiring example with peripheral equipment CN2 Encoder socket ...
Page 242: ...234 12 4 Version information Version V1 01 Issue date Aug 2017 Proofreader Yaochou Shu ...