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Commissioning
Digistart IS User Guide 79
Issue: 4 www.controltechniques.com
10.6 Soft braking
For applications with high inertia and/or a variable load, the Digistart IS can be configured for soft braking.
In this application the Digistart IS is employed with forward run and braking contactors. When the Digistart IS receives a start signal
(pushbutton S1), it closes the forward run contactor (KM1) and controls the motor according to the programmed primary motor
settings.
When the Digistart IS receives a stop signal (pushbutton S2), it opens the forward run contactor (KM1) and closes the braking
contactor (KM2) after a delay of approximately 2-3 seconds (KT1). KA3 is also closed to activate the secondary motor settings,
which should be user programmed for the desired stopping performance characteristics.
When motor speed approaches zero, the zero speed detector (A2) stops the soft starter and opens the braking contactor (KM2).
Figure 10-6 Soft braking
Control voltage (model dependent)
Zero speed detector relay
Zero speed detector delay timer*
Semiconductor fuses (optional)
* The KT3 timer is only required if the zero speed detector is the type that performs a self-test upon power-up and momentarily
closes the output relay.
Parameter settings:
Pr 3A Input A Function (terminals DI4, +24V)
Select 'Motor Set Select' - assigns Input A for Motor set selection.
Set starting performance characteristics using the primary motor set.
Set braking performance characteristics using the secondary motor settings.
Pr 4G Relay C Function
Select 'Trip' - assigns Trip function to Relay Output C.
If the Digistart IS trips on supply frequency (Pr 16H Frequency) when the braking contactor KM2 opens, modify the
frequency protection settings.
2
1
6
3 4
7
1
5
CSH CSRCSL
TH1 PT3
TH2
COM4
RLC4
DI3
DI1
DI2
DI4
+24V
08537.B
PT4 PT5
+24V
+24V +24V
110-210 VAC
220-440 VAC
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