Dc Injection Braking - SAF Opal Pro MS6 Series Installation & Operating Procedures

MS6 REDUCED VOLTAGE STARTER

7.7 DC INJECTION BRAKING

• DC injection braking provides smooth braking for AC induction motors.
• DC injection offers adjustable braking because it is current controlled.
• Unlike a mechanical brake, an electrical brake will never wear out.
• The brake operates by injecting DC current in two phases of the motor to rapidly decelerate
it to zero speed.
• When stop is commanded the Opal Pro shuts off for 2 seconds to allow the voltage across
the motor to drop. The DC injection current is then applied at a level set in parameter 1104
for the amount of time set in parameter 1105. It does not provide zero speed sensing,
although if two wire control is used terminal 4 can be used to disable the DC injection
(activated = enabled).
• If braking is released before the motor stops, the motor will coast to rest. If the braking
remains on after the motor stops, the DC supply will provide a holding brake.
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