Rockwell Automation Publication MPAI-IN001F-EN-P - January 2016
7
MP-Series Heavy-duty Electric Cylinders
Electric Cylinders with Brake Option
The brake option on this servo motor is a spring-set holding brake that releases when voltage is
applied to the brake coil. A separate power source is required to disengage the brake. This power
source can be applied by a servo motor controller or manual operator control.
If system main power fails, holding brakes can withstand occasional use as stopping brakes.
However, this creates rotational mechanical backlash that is potentially damaging to the system,
increases brake wear, and reduces brake life.
An electric cylinder not under powered requires a brake to maintain its position if the force on
the actuator exceeds the Back Drive Force listed in Kinetix® Linear Motion Specifications
Technical Data, publication
GMC-TD002.
A brake can be use with the actuator to keep it from back driving, typically in vertical
applications. A brake can be used for safety reasons or for energy savings allowing the actuator to
hold position when not under power.
Preventing Electrical Noise
Electromagnetic interference (EMI), commonly called electrical noise, can reduce motor
performance. Effective techniques to counter EMI include filtering the AC power, by using
shielded cables, separating signal cables from power wiring, and practicing good grounding
techniques.
Follow these guidelines to avoid the effects of EMI:
•
Isolate the power transformers or install line filters on all AC input power lines.
•
Physically separate signal cables from motor cabling and power wiring. Do not route
signal cables with motor and power wires, or over the vent openings of servo drives.
•
Ground all equipment by using a single-point parallel ground system that employs
ground bus bars or large straps. If necessary, use additional electrical noise reduction
techniques to reduce EMI in noisy environments.
See System Design for Control of Electrical Noise Reference Manual, publication
GMC-RM001
, for additional information on reducing the effects of EMI.
IMPORTANT
Holding brakes are not designed to stop rotation of the motor shaft, nor are they intended to be
used as a safety device. They are designed to hold a motor shaft at 0 rpm for up to the rated
brake holding torque.
The recommended method of preventing motor shaft rotation is a four-step process: first,
command the servo drive to 0 rpm; second, verify the motor is at 0 rpm; third, engage the
brake; and fourth, disable the drive.
Disabling the drive removes the potential for brake wear caused by a badly-tuned servo system
oscillating the shaft.
