Ametek Dycor Dymaxion Mass Spectrometer, User Manual

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viii | Dycor Dymaxion Mass Spectrometer
Electromagnetic Compatibility (EMC)
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.
The various configurations of the Dymaxion should not produce, or fall victim to, electromagnetic dis-
turbances 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 situ-
ations. In addition, hard conduit, flexible conduit, and armor around non-shielded wiring also provides
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 allow-
ing high frequency shield bonding while avoiding the AC-ground metal connection. In the case of shield-
ed cables the drain wire or braid connection must be kept short. A two-inch connection 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 unshieled 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 elec-
trical events and devices known for the generation of harmful electromagnetic disturbances include mo-
tors, capacitor bank switching, storm related transients, RF welding equipment, static, and walkie-talkies.