Parker H Series, Инструкция по установке и обслуживанию

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Industrial Automation Wiring and Grounding Guidelines E115P
14
Surge-suppressors are usually most effective when
connected at the inductive loads. They are still usable
when connected at the switching devices; however, this
may be less effective because the wires connecting the
switching devices to the inductive loads act as antennas
that radiate EMI. You can see the effectiveness of a
particular suppressor by using an oscilloscope to observe
the voltage waveform on the line.
Ferrite Beads
Ferrite beads can provide additional suppression of
transient EMI. Fair-Rite Products Corporation
manufactures a ferrite bead (part number 2643626502)
which can be slipped over category-2 and -3 conductors.
You can secure them with heat-shrink tubing or tie-wraps.
With a ferrite bead located near the end of a cable (or
cable segment in the case of a daisy-chain or dropline
configuration) transient EMI induced onto the cable can
be suppressed by the bead before it enters the equipment
connected to the end of the cable.
Enclosure Lighting
Fluorescent lamps are also sources of EMI. If you must
use fluorescent lamps inside an enclosure, the following
precautions may help guard against EMI problems from
this source as shown in Figure 12:
• Install a shielding grid over the lamp
• Use shielded cable between the lamp and its switch
• Use a metal-encased switch
• Install a filter between the switch and the power line,
or shield the power-line cable
Avoiding Unintentional Momentary
Turn-On of Outputs
Unintentional turn-on of outputs as the power source is
connected or disconnected, even if momentary, can result
in injury to personnel as well as damage to equipment.
The danger is greater with fast-response actuators. You
can help minimize the probability of unintentional momentary
turn-on of AC and DC circuits by following each of these
guidelines according to your specific application:
• Follow the surge-suppression guidelines in this
publication
• Follow the bonding and grounding guidelines in this
publication
• Do not unnecessarily disconnect the power source
from output circuits
• Where possible, turn off all outputs before using CRM
contacts to interrupt the output circuit power source
• Hold off all outputs anytime the CRM contacts are
open to be certain that they are off as power is
reconnected
Even if unintentional momentary turn-on does occur, the
effects can be minimized if:
• Actuators have a home position, i.e. defined by a
spring return
• For latching actuators, in the ladder logic, use non-
retentive energize (OTE) instructions with hold-in (seal-
in) paths to maintain the established position until power
turn-off and leave outputs off initially at power turn-on
• Each input or other load device connected to an output
has an input-filter time constant no lower than
necessary for the application
After designing and installing your system following these
guidelines to minimize unintentional momentary turn-on
and any effects thereof, test the system by de-energizing
and then re-energizing the CRM relay (Figures 7 and 8).
Related Publications
For additional information regarding wiring and grounding
guidelines, refer to:
• Application Considerations for Solid-State Controls
(publication E116P) — this is an aid to the user of
solid-state controls who has considerable familiarity
with relay-type controls but may have limited electronic
experience and knowledge.
Figure 12 – Installation Requirements for Suppressing
Noise From Fluorescent Lamps Inside an Enclosure
Filter
Shielding-Grid
Over Lamp
Shielded
Cable
Metal-Encased
Switch
Line-Filter or
Shielded
Power Line
AC Power