M3452 vR8 EIP/PDP
62
VDC, for 230 VAC systems, it is typically 375 VDC. Refer to your drive
manual for specifics.
For the above example, the ohmic value would be:
ohms
watts
VDC
R
brake
26.1
447600
)750(
2
This value must be verified with the ratings of the braking transistor
module selected that it is not less than the “minimum ohmic value” for that
model. If so, the braking requirements may be more than the braking
transistor module can absorb, and a larger module may be required.
It is also possible to parallel two modules with two separate braking
resistors to achieve the braking power required.
If the ohmic value calculated is greater than the value listed in the ratings
table, it is possible to select a resistor value lower than the calculated
value.
7.1.1.4. DUTY CYCLE
The duty cycle is based on the amount of time the drive is actually braking
as opposed to accelerating, running at constant speed, or idle. For
instance, if a pick and place operation requires 3 seconds to accelerate,
traverses for 44 seconds and then decelerates for 3 seconds, the total
cycle time is:
sec503443
decrunacccycle
TTTT
The duty cycle for braking is:
This rating assumes the load will be linearly decreasing from peak braking
power to zero braking as the load comes to a stop.
Check this rating against the modules duty cycle rating, and if it is higher
than rated, go to the next higher rated module. If a duty cycle is required
over 50%, please call for assistance with your application.
7.1.1.5. CONTINUOUS RATING
The continuous rating is listed for long term heating calculations should
the unit be installed in an area where heat dissipation is an issue. The
rating is based on a triangular cycle that starts at peak value and reduces
to zero within the rated duty cycle. Therefore, the average braking power
during the deceleration cycle is ½ the power required if full power was
required during the entire braking cycle. This value is:
2/%*
dutypeakcontinuous
PP
For the above example, the
WP
continuous
134282/%6*447600W
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