Banner MMD-TA-11B Muting Modules - Manual (Page 20)

18
P/N 116390 rev. C
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
WARNING . . . Avoid Hazardous
Installations
Two or four independent position switches (at
M1–M2 or M3–M4) must be properly adjusted or positioned
so that they close only after the hazard no longer exists,
and open again when the cycle is complete or the hazard
is again present. If improperly adjusted or positioned,
injury or death could result.
The user has the responsibility to satisfy all local, state, and
national laws, rules codes, and regulations relating to the use
of safety equipment in any particular application. It is extremely
important to be sure that all appropriate agency requirements
have been met and that all installation and maintenance
instructons contained in the appropriate manuals are followed.
3.5.2 Muting Devices
The user is required by OSHA and ANSI to arrange, install,
and operate the safety system so as to protect personnel and
minimize the possibility of defeating the safeguard.
Mute devices must meet a 3-second simultaneity requirement to
activate muting; that is, devices in a pair must be activated within
3 seconds of one another.
General Muting Device Requirements
The muting devices (typically sensors or switches) must, at a
minimum, comply with the following requirements:
1. There must be a minimum of two independent hard-wired
muting devices.
2. The muting devices must either both have normally open
contacts; or one device with a PNP output and one device
with a NPN output, both of which must fulfill the input
requirements listed in the Specifications (Section 2). These
contacts must close when the switch is actuated, and must
open (or not conduct) when the switch is not actuated or in a
power OFF condition.
3. The activation of the inputs to the muting function must be
from separate sources. These sources must be mounted
separately in order to prevent an unsafe muting condition
resulting from misadjustment, misalignment, or a single
common mode failure. (For example, physical damage to
the mounting surface could cause both muting devices to
be knocked out of alignment, resulting in false muting input
signals.) Only one of these sources may pass through, or be
affected by, a programmable logic controller or similar device.
4. The muting devices must be installed so that they can not be
easily defeated or bypassed.
5. The muting devices must be mounted so that their physical
position and alignment can not be easily changed.
6. It must not be possible for environmental conditions to initiate
a mute condition (e.g., extreme airborne contamination).
7. The muting devices must not be set to use any delay or other
timing functions (unless such functions are accomplished so
that no single component failure prevents the removal of the
hazard, subsequent machine cycles are prevented until the
failure is corrected, and no hazard is created by extending the
muted period).
Examples of Muting Sensors and Switches
Photoelectric Sensors (Opposed Mode): Opposed-mode
sensors, which initiate the muted condition when the beam path
is blocked, should be configured for dark operate (DO) and have
open (non-conducting) output contacts in a power OFF condition.
Both the emitter and receiver from each pair should be
powered from the same source, to eliminate common mode
failures.
Photoelectric Sensors (Polarized Retroreflective Mode): The
user must ensure that false “proxing” (activation due to shiny
or reflective surfaces) is not possible. Banner “LP” sensors with
linear polarization can greatly reduce or eliminate this effect.
Use a sensor configured for Light Operate (LO or N.O.) if
initiating a mute when the retroreflective target or tape is
detected (e.g., home position). Use a sensor configured for Dark
Operate (DO or N.C.) when a blocked beam path initiates the
muted condition (e.g., entry/exit). Both situations must have open
(non-conducting) output contacts in a power OFF condition.
Positive-Opening Safety Switches: Two (or four) independent
switches, each with a minimum of one closed safety contact to
initiate the mute cycle, are typically used. An application using
a single switch with a single actuator and two closed contacts
could result in an unsafe situation.
Inductive Proximity Sensors: Typically, inductive proximity
sensors are used to initiate a muted cycle when a metal surface
is detected. Due to excessive leakage current causing false ON
conditions, two-wire sensors are not to be used. Only three- or
four-wire sensors that have discrete PNP, NPN, or hard-contact
outputs that are separate from the input power can be used.