Banner MMD-TA-11B Muting Modules - Manual (Page 25)

P/N 116390 rev. C
23
Banner Engineering Corp. • Minneapolis, U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
MMD-TA-11B / MMD-TA-12B Muting Module
Instruction Manual
System Installation
Category 4
To ensure a category 4 application, any device connected to the
SSI and MSSI inputs must meet certain criteria. For example, a
“type 4” safety light screen (curtain) that meets IEC 61496-1/-2 is
a device that meets category 4 requirements.
In a category 4 application, a single fault must not cause the loss
of the safety function. The fault must be detected at or before
the next demand of the safety function, and an accumulation of
faults also must not cause the loss of the safety function.
This is usually accomplished by the use of redundant safety
inputs or outputs from the safety-rated device that are monitored
to detect certain faults. These faults include:
• Increased response time
• Prevention of one or more safety outputs (OSSDs) going to the
OFF-state
• A short circuit between channels
NOTE: Solid-state safety outputs, such as those from
EZ-SCREEN Type 4 safety light screens, typically
achieve this level of fault tolerance by self-monitoring a
pulsing of the outputs. Safety devices with hard-contact
or relay outputs must be connected in a “4-wire” method
as shown in Figure 3-15c.
The principle of fault exclusion must be incorporated into the
design and installation to either eliminate, or reduce to an
acceptable (minimal) level of risk, the possibility of catastrophic
failures/faults that could result in the loss of the safety function.
Figure 3-15a. MSSI and SSI Category 4 interfacing: two
positive-opening switches per single guard
(a)
MSSI or SSI
(b)
(c)
(d)
A1
X6
X5
X7
X8
S12
S11
S21
S22
+24V dc 0V
MMD-TA-..B
A2
Figure 3-15b. MSSI and SSI Category 4 interfacing: category 4
safeguarding device with output fault monitoring
(e.g., EZ-SCREEN or AOPD Type 4 per IEC 61496-
1/-2)
+24V dc
EZ-SCREEN
Type 4
0V
(a)
MSSI or SSI
(b)
(c)
(d)
MMD-TA-..B A1
S12
S11
A2
+
+
S22
S21
X6
X5
X8
X7
Figure 3-15c. MSSI and SSI Category 4 interfacing: category 4
safeguarding device with relay outputs (e.g.,
MINI-SCREEN or AOPD Type 4 per IEC 61496-1/-2)
(a)
MSSI or SSI
(b)
(c)
(d)
A1
X6
X5
X7
X8
S12
S11
S21
AOPD
Type 4
S22
+24V dc 0V
MMD-TA-..B
A2