Banner SCR P Series Instruction Manual page 27

CAUTION: Machine Control Must Provide Anti-Repeat Control
Appropriate anti-repeat control must be provided by the machine control and is required by U.S. and
International standards for single-stroke or single-cycle machines.
This Bernstein device can be used to assist in accomplishing anti-repeat control, but a risk assessment
must be accomplished to determine the suitability of such use.
Two-Hand Control Safety Distance (Minimum Distance)
The hand controls operator must not be able to reach the hazardous area with a hand or any other body part before the
machine motion ceases. Use the formula below to calculate the safety distance (minimum distance).
WARNING: Location of Touch Button Controls
Hand controls must be mounted a safe distance from moving machine parts, as determined by the
appropriate standard. It must not be possible for the operator or other non-qualified persons to relocate
them. Failure to establish and maintain the required safety distance could result in serious injury or death.
U.S. Applications
The Safety Distance formula, as provided in ANSI B11.19:
Part-Revolution Clutch Machinery
D s = K x (T s + T r ) + D pf
For Full-Revolution Clutch Machinery
D s = K x (T m + T r + T h )
D s
the Safety Distance (in inches)
K
the OSHA/ANSI recommended hand-speed constant (in inches per second), in most cases is calculated at 63 in/sec, but may vary between
63 in/sec to 100 in/sec based on the application circumstances;
not a conclusive determination; consider all factors, including the physical ability of the operator, when determining the value of K to be used
T h
the response time of the slowest hand control from the time when a hand disengages that control until the switch opens;
T h is usually insignificant for purely mechanical switches. However, T h should be considered for safety distance calculation when using
electronic or electromechanical (powered) hand controls. For BERNSTEIN Self-checking Touch Buttons (STBs) the response time is 0.02
seconds
T m
the maximum time (in seconds) the machine takes to cease all motion after it has been tripped. For full revolution clutch presses with only one
engaging point, T m is equal to the time necessary for one and one-half revolutions of the crankshaft. For full revolution clutch presses with more
than one engaging point, T m is be calculated as follows:
T m = (1/2 + 1/N) x T cy
N = number of clutch engaging points per revolution
T cy = time (in seconds) necessary to complete one revolution of the crankshaft
T r
the response time of the Safety Controller as measured from the time a stop signal from either hand control. The Safety Controller response
time is obtained from the Configuration Summary tab in the Software.
T s
the overall stop time of the machine (in seconds) from the initial stop signal to the final ceasing of all motion, including stop times of all
relevant control elements and measured at maximum machine velocity
T s is usually measured by a stop-time measuring device. If the specified machine stop time is used, add at least 20% as a safety factor to
account for brake system deterioration. If the stop-time of the two redundant machine control elements is unequal, the slower of the two times
must be used for calculating the separation distance
(the machine and its controls allow the machine to stop motion during the hazardous portion of the machine cycle)
(the machine and its controls are designed to complete a full machine cycle)
www.bernstein.eu
Programmable Safety Controller SCR P
- Tel: + 49 571 793 0 27