Tech Briefs Magazine - April 2021 - MD-8

Smart Sense Spring Set Brake Controller - Smart Holding Voltage Time
No Wasted Time

(t+)

Worn
Holding

New

Voltage

Disengagement

0.25

1.5

0.5
Time Seconds

Figure 2. Smart brake control disengagement of a new brake (green line) and a worn brake (red line).

controls do not reduce the applied voltage to the holding voltage prior to the
brake fully disengaging. At any point in
the life of the brake, the amount of time
beyond the full disengagement before
the voltage is reduced to the holding voltage is shown in Figure 1 as Wasted Time.
Standard brake controls are unable to
respond to the condition of the brakes
and do not provide the user with information about brake performance. The
controls will continue to operate regardless of whether the brake is operational.
The brake will operate until it can no
longer disengage, resulting in catastrophic failure that may also adversely
affect other drive system components.
Only through frequent visual inspections of the brake friction elements
could a user assess the worn condition of
a brake and often, such inspections are
not feasible or cost-effective.

New Smart Control
Technology
The new smart IloT brake controller
detects motion in the brake armature
and utilizes this information to accurately
determine when the brake is disengaged,
then automatically reduces the full activation voltage to the preset holding voltage.
The detection of the armature motion is
communicated to the user in real time. In
addition, data is collected and analyzed
from cycle to cycle to assess the overall
condition of the brake and drive system,
with abnormalities reported to the user.
Providing such otherwise unavailable
data allows the user to maximize efficiencies while minimizing failure risk.

The standard brake user's overestimate
or underestimate of time to full disengagement is eliminated with the new
smart brake controls. Precise tracking of
armature motion allows the smart sense
controls to reduce the voltage to the holding voltage with negligible (t+) response
delay. The voltage reduction occurs when
the brake armature moves, regardless of
variations in temperature, operation,
environmental conditions, or brake wear.
Figure 2 illustrates smart brake control
disengagement of a new brake (green
line) and a worn brake (red line). The
time before the controls reduce the activation voltage to the holding voltage accurately tracks by (t+) the actual disengagement time from the brake's new condition to its fully worn condition.
For example, operational temperature changes may result from factors
such as cycle rate variations, torsional
load changes, and environmental conditions. The temperature changes affect
the brake's capability to thermally expel
heat and consequently affect brake disengagement time. The smart brake controls automatically adjust for any disengagement time variations by accurately
reading the actual disengagement time.
The precise tracking feature of smart
controllers, in combination with its digital signal output, resolves a performance
issue specific to holding brakes. When a
holding brake releases its torsional load,
the motor takes control of the load. An
overestimate of the release time causes
" drift " of the load before the motor
takes control. By digitally notifying the
motor controller in real time when the

brake is fully released, the smart controller effectively eliminates any drift.
Beyond notifying the user of brake disengagement, the controls offer several
other digital and analog outputs in real
time. For example, the smart controller
communicates abnormal brake cycles,
which may be an indication that the
drive system's bearings are approaching
failure. The controls also estimate brake
life based on the wear generated from
prior cycles and notify the user of the
worn condition of the brake. The information may be used to schedule brake
maintenance to avoid brake failure.
In some cases, catastrophic system failure may also be avoided. For example, a
system that is being operated beyond its
means with high cycle rates or excessive
loads will generate extreme heat, causing
the brake to cease disengaging. With a
standard brake control, the user would not
be able to identify the issue until the drive
system failed. With new brake controls, if a
brake is no longer able to disengage, by
monitoring the controls, the brake failure can be determined by the user.
Ease of installation and integration
further enhance the value of the new
technology. Free of external sensors, the
smart sense controls are fully interchangeable with existing standard controls. The smart brake controls provide
analog (brake wear) and digital (brake
disengagement and 80% worn condition) outputs that may be connected to
smart motor controllers and/or monitoring software such as HMI or IoTenabled software.

Summary
The new, innovative smart controller
internally senses, captures, and makes
use of brake armature movement to provide sensorless optimization of spring
set/electrically released brakes, conserving power and maximizing brake life.
Previously unavailable analog and digital
outputs allow users to monitor armature
position and movement, providing key
insights into brake wear that help the
user get the most out of the brake and
improve the drive system. The controls
may be seamlessly integrated with monitoring software to provide complete
remote monitoring of critical systems.
This article was written by Michael Gamache,
President, Carlyle Johnson Machine Company
and Regent Controls, Greenville, RI. For more
info, visit http://info.hotims.com/79412-283.
Motion Design, April 2021

Cov

ToC

http://info.hotims.com/79412-283 http://www.abpi.net/ntbpdfclicks/l.php?202104TBNAV

Tech Briefs Magazine - April 2021

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