10-2 Additional Setup 3AXD50000011888
10.1.1 Parameter Settings
Trickle Current Enable (74.01) Default: 0 (Disable)
Range: 0 - 4
0 (Disable) Disable trickle current
1 (Enable) Enable trickle current whenever motor is not running
3 (FBA) Enable trickle current over Fieldbus Adapter Module
4 (EFB) Enable trickle current over Embedded Fieldbus
Trickle Power (74.02) Default: 100W
Range: 0 to 1000W
The level of trickle current is determined by frame size of the motor.
Trickle Current Delay (74.03) Default: 1 Min
Range: 0 - 10 Min
The time delay before trickle current starts. This delay ensures the motor has
ramped down and stopped prior to trickle current beginning.
10.1.2 CTDD Assistant Access
In addition to programming changes in group 74, Trickle Current is an option under the CTDD startup assistant:
Figure 10-1 Trickle Current
00:00Back
50.0 rpmLocal
Trickle Current
Set parameters for Trickle Current.
Enable
Trickle Power
Next
Disabled
100W
CTDD
10.2 Critical Speed Function
When applying a variable speed control to a cooling tower fan, mechanical resonances may occur at various points of
operation. The ACS880+N5350 provides for up to three frequency avoidance bands that are used to prohibit continuous
operation at the points of mechanical resonance.
While in LOCAL control, the keypad can be used to start and stop the drive and to locally adjust the speed.
Use the “UP” arrow key to slowly increase the speed of the motor. Should the cooling tower fan start to resonate, record the
RPM. Continue this process until you have tested the motor at all points between minimum speed and maximum speed.
The parameters that are used to provide for the critical speeds are located in the Speed Reference Selection Block
(parameter numbers 22.51 through 22.57). Program a band around each point of resonance using parameter settings critical
speed low and high.
For a more detailed description of these parameters see Chapter 12.
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