Manual

page 5
Safety Extension Modules – EM-FD-7G Series with Delayed Output
WARNING . . .
Use of Arc Suppressors
If arc suppressors are used, they
MUST be installed as shown across
the actuator coil of the master stop
control elements (MSC1 to MSC4).
NEVER install suppressors directly
across the output contacts of the
Safety Extension Module. It is
possible for suppressors to fail as a
short circuit. If installed directly
across the output contacts of the
Safety Extension Module, a short-
circuited suppressor will create an
unsafe condition which could result
in serious injury or death.
!
WARNING . . .
Maintain Control
Reliability
NEVER wire an intermediate device
(e.g., a programmable logic
controller/ PLC), other than a safety
relay, between any safety output of
the Safety Extension Module and the
master stop control element it
switches. To do so sacrifices the
control reliability of the control-to-
machine interface, and creates an
unsafe condition which could result in
serious injury or death. Whenever a
safety relay is added as an
intermediate switching device, a
normally-closed forced-guided monitor
contact of that relay must be added to
the series feedback loop.
(Reference ANSI B11.1 – 1988,
Appendix B4)
!
EM-FD-XXX
0
V dc
+24V ac/dc
L1
L2
Machine Control Element
Primary
Safety
Device
Monitoring Contact
Feedback Input
Monitoring Contact
Feedback Input
MSC1
MSC Monitor Contacts
NOTE:
This hookup is general in nature.
Your specific hookup may vary significantly,
depending on the Primary Safety Device
used and the machine control configuration.
MSC2 MSC3 MSC4
MSC1
*
MSC2
*
MSC3
*
*
Machine
Master Stop
Control Elements
*Arc Suppressors
(See Warning)
27
Y1 Y2
48 A247
28
17
18
A1
37
38
MSC4
Figure 3. Generalized EM-FD-7G Series hookup
One-Channel Control (Figure 3)
One-channel control affords simplicity of wiring. However, one-channel wiring
requires eliminating the possibility of an unsafe failure of the control wires (which
connect the output of the Primary Safety Device to the input of the Extension
Module). One of the ways to reduce the probability of such failure is to locate the
Primary Safety Device adjacent to the Safety Extension Module, in the same
enclosure.
The output of the Primary Safety Device must consist of two or more series-
connected, normally open contacts, coming from forced-guided safety relays. These
contacts must be monitored for failure by the Primary Safety Device. In addition, a
single contact failure cannot prevent normal stopping action, and a successive cycle
cannot be initiated until the failure has been corrected. An example of this type of
output is any single output channel of a Banner E-stop safety module.
Use of Multiple Safety Extension Modules
Multiple Safety Extension Modules may be series-connected to provide additional
output channels. However, the delay time of each Safety Extension Module must be
added to the delay (or response) time(s) of the Primary Safety Device and all Safety
Extension Modules ahead of it in the circuit to determine its total output response
time (see Figure 4).
Whenever more than one Safety Extension Module is controlled by one Primary
Safety Device, the monitoring contacts of all Safety Extension Modules (terminals
Y1 and Y2) must be wired together in series and connected to the Monitoring
Contact Feedback Input of the Primary Safety Device.
Primary
Safety
Device
100 ms
delay
100 ms
total delay
Safety
Extension
Module #1
500 ms
delay
600 ms
total delay
Safety
Extension
Module #2
500 ms
delay
1.1 sec
total delay
Safety
Extension
Module #3
500 ms
delay
1.6 sec
total delay
etc.
Figure 4. Figuring the total delay
response of each Safety
Extension Module in a
multiple-module circuit