4-19
Controlling Initial Start of Car Motion
iControl AC
4
Brake Parameter Adjustments
The iField braking module allows you to make some very refined brake adjustments for smooth
picking to control rollback.
• First, find the level of brake excitation that results in a very gradual but complete picking
of the brake:
1. Place the car on Inspection (iBox Inspection switch in the INSP position). Set Pattern
Scaling (Pattern/Common tab) to 10% to provide an inspection speed of about 5 to 10
fpm.
Figure 4.3 Brake timing diagram for smooth picking
2. Display the Configuration > Brake > Control tab and record the original parameters
before making any changes. Verify the following settings:
• Weakening delay = 0.00
• Repick time = 0.00
3. Set the Pick voltage and the Hold voltage to ½ of the original value of Pick voltage.
4. Slowly increase both Pick and Hold voltages until the brake picks completely. The idea is
to increase or decrease both Pick voltage and Hold voltage identically until the brake
just barely picks all the way. Then, add 5 or 10 volts and verify that the brake still has a
very slow, smooth picking motion (taking 1 to 1.5 seconds to pick). The goal is to find a
brake voltage that allows the brake to transition slowly through the pressure-releasing
part of the movement.
5. Set the Weakening voltage to the same value as Pick Voltage and Hold Voltage. For
geared applications, if the brake holding voltage is not specified, set Weakening voltage
and Hold voltage = Pick voltage.
Pick Voltage
Hold Voltage
Weakening Voltage
Motor
Contactor/
Drive Enable
Brake
Contactor
Doors Locked High
Pick Delay
Weakening
Delay
Repick
Time
Hold Delay
Speed Pick Delay 1 Timer
Pattern
Applied
80% of Pick
Voltage
Smooth Pick
Pattern
Brake
Door Open
Limit High
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