2-10
This was known because the drive is rated at 480 Volts rms. If the drive
were rated 230 Volts rms, then V
d
= 375 Volts.
All of the preceding data and calculations were made from knowledge of
the application under consideration. The total inertia was given and did
not need further calculations as outlined in
Step 2.
Note that this is 8.1% of rated power and is less than the maximum drive
limit of 150% current limit. This calculation is the result of
Step 3 and
determines the peak power that must be dissipated by the Dynamic
Brake Resistor.
This is the result of calculating the average power dissipation as outlined
in
Step 5. Verify that the sum of the power ratings of the Dynamic Brake
Resistors chosen in
Step 4 is greater than the value calculated in Step 5.
Refer to
Table 2.A to determine the continuous power rating of the
resistor in the given drive frame you are using. You will need this
number to determine the Percent Average Load and the Percent Peak
Load.
This is the result of the calculation outlined in
Step 6. This point is
plotted at the decel time of the application moving up vertically to this
percentage.
V
d
750 Volts=
Peak Braking Power P
b
J
T
ω
b
ω
b
ω
o
–()[]
t
3
t
2
–()
----------------------------------------==
P
b
0.261 186.92 186.92 0–()[]
15
------------------------------------------------------------- 608.6 watts==
Average Braking Power P
av
t
3
t
2
–()
t
4
------------------
P
b
2
-----
ω
b
ω
o
+()
ω
b
------------------------
==
P
av
15
40
-----
608.6
2
------------
186.92 0+
186.92
------------------------
114.1 watts==
Percent Average Load AL 100
P
av
P
db
--------
×==
AL 100
114.1
40
------------ 285%=×=
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