5–6

Dynamic Braking

Dynamic Braking Usage Ratio

The inverter controls braking via a duty cycle

BRD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

method (percent of the time braking is ON

 

 

 

 

t1

 

 

 

 

 

 

t2

 

 

 

 

 

 

t3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

versus total time). Parameter B090 sets the

ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

dynamic braking usage ratio. In the graph to

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

the right, the example shows three uses of

OFF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

dynamic braking in a 100-second period. The

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

inverter calculates the average percentage

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(t1 + t2 + t3)

 

 

 

t

usage in that time (T%). The percentage of

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

T% =

⋅

100

 

 

 

 

 

B 90

------------------------------

 

 

 

 

usage is proportional to the heat dissipated. If

 

 

 

 

 

 

100 seconds

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

T% is greater than the B090 parameter setting,

the inverter enters the Trip Mode and turns OFF the frequency output.

Please note the following:

•When B090 is set for 0%, dynamic braking is not performed.

•When the T% value exceeds the limit set by B090, dynamic braking ends.

•When mounting an external dynamic braking unit, set the usage ratio (B090) to 0.0 and remove the external resistors.

•The cable from the external resistor to the inverter must not exceed 5 m (16 ft.) length.

•The individual wires from the resistor to the inverter must not be bundled together.

Motor Control

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