Example Separation Distance (D
s
) Calculation
The following example illustrates the use of the formula to calculate separation distance for a part-revolution clutch machine. This
example uses 0.50 seconds as a typical value for T
s
and 0.02 seconds for T
h
:
K
= 63" per second
T
s
= 0.50 seconds (measured by a stop-time measuring device)
T
r
= 0.035 seconds
T
h
= 0.02 seconds
D
s
= K x (T
s
+ T
r
+ T
h
)
= 63" (0.50 + 0.035 + 0.02)
= 35"
In this example, both hand controls must be located no closer than 36" from the nearest hazard point.
NOTE:
1. The OSHA-recommended hand speed constant K has been determined by various studies, and
although these studies indicate speeds of 63"/sec to over 100"/sec, they are not conclusive deter-
minations. The employer should consider all factors, including the physical ability of the operator,
when determining the value of K to be used.
2. 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.
3. T
h
is usually insignificant for purely mechanical switches. However, T
h
should be considered for
separation distance calculation when using electronic or electromechanical (i.e. powered) hand
controls. In this example, STB response time = 0.02 seconds.
Electrical Installation
Because the DUO-TOUCH SG Safety Module interfaces to many types of machine controls, it is not possible to give exact wiring instruc-
tions here. The following guidelines are general in nature.
CAUTION: Disconnect Power Before Wiring
Before making any wire connections, make certain all power is disconnected from the Safety Mod-
ule and the machine to be controlled.
Electrical installation of hand controls, the DUO-TOUCH SG Safety Module, and the interconnection to the
machine control must be made by qualified personnel and must comply with NEC (National Electrical
Code), ANSI/NFPA79 or IEC60204-1, and all applicable local standards.
Dangerous voltages may be present along the Safety Module wiring barriers whenever power to the ma-
chine control elements is ON. Exercise extreme caution whenever machine control power is or may
be present. Always disconnect power to the machine control elements before opening the enclo-
sure housing of the Safety Module.
DUO-TOUCH
®
SG Two-Hand Control Modules
10
www.bannerengineering.com - tel: 763-544-3164
P/N 109782 Rev.B