Electromagnetic Compatibility (Emc) - Ametek 241CE II User Manual

Electromagnetic Compatibility (EMC)

The various configurations of the 241CE II Analyzer should not produce, or fall victim to, electromagnetic
disturbances as specified in the European Union's EMC Directive. Strict compliance to the EMC Directive
requires that certain installation techniques and wiring practices are used to prevent or minimize erratic
behavior of the Analyzer or its electronic neighbors. Below are examples of the techniques and wiring
practices to be followed.
In meeting the EMC requirements, the various Analyzer configurations described in this manual rely
heavily on the use of metallic shielded cables used to connect to the customer's equipment and power.
Foil and braid shielded I/O and DC power cables are recommended for use in otherwise unprotected
situations. In addition, hard conduit, flexible conduit, and armor around non-shielded wiring also pro-
vides excellent control of radio frequency disturbances. However, use of these shielding techniques is
effective only when the shielding element is connected to the equipment chassis/earth ground at both
ends of the cable run. This may cause ground loop problems in some cases. These should be treated on
a case-by-case basis. Disconnecting one shield ground may not provide sufficient protection depending
on the electronic environment. Connecting one shield ground via a 0.1 microfarad ceramic capacitor is a
technique allowing high frequency shield bonding while avoiding the AC-ground metal connection. In
the case of shielded cables, the drain wire or braid connection must be kept short. A two-inch connec-
tion distance between the shield's end and the nearest grounded chassis point, ground bar or terminal is
highly recommended. An even greater degree of shield performance can be achieved by using metallic
glands for shielded cable entry into metal enclosures. Expose enough of the braid/foil/drain where it
passes through the gland so that the shield materials can be wrapped backwards onto the cable jacket
and captured inside the gland, and tightened up against the metal interior.
Inductive loads connected to the low voltage "Alarm Contacts" are not recommended. However, if this
becomes a necessity, adhere to proper techniques and wiring practices. Install an appropriate transient
voltage suppression device (low voltage MOV, "Transzorb, " or R/C) as close as possible to the inductive
device to reduce the generation of transients. Do not run this type of signal wiring along with other I/O
or DC in the same shielded cable. Inductive load wiring must be separated from other circuits in conduit
by using an additional cable shield on the offending cable.
In general, for optimum protection against high frequency transients and other disturbances, do not
allow installation of this Analyzer where its unshielded I/O and DC circuits are physically mixed with AC
mains or any other circuit that could induce transients into the Analyzer or the overall system. Examples
of electrical events and devices known for the generation of harmful electromagnetic disturbances
include motors, capacitor bank switching, storm related transients, RF welding equipment, static, and
walkie-talkies.
PN 903-8797, Rev A
Read and follow the recommendations in this section to avoid performance
variations or damage to the internal circuits of this equipment when installed
in harsh electrical environments.
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