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Section 3: Instrument
9
3. Instrument
3.1 Precautions using the XDT
The XDT uses state-of-the-art microelectronics to provide a compact full functioning instrument.
The user should consider the following precautions when using any sensitive electronic device.
• Observe the appropriate electrical safety codes and regulations. Consult with National Electri-
cal Code article 400, and/or other nationally or locally recognized procedures relevant to your
installation. You will most probably require a disconnect switch, and power wiring. The
power cord provided with the instrument is intended only for testing, it may not be used for a
permanent field wired installation. This instrument is UL approved for field wiring.
• If weather proofing is required consult your representative for an optional enclosure. The
XDT is not intended for direct outdoor installation unless it is appropriately housed.
• Do not install the unit near heat sources such as radiators or air ducts.
• Do not install the unit in places subject to extreme mechanical vibration or shock. If this is not
avoidable, use resilient mounting. If in doubt, call your representative.
• Before handling the circuit board outside its enclosure, discharge any static electricity bildup
on your person by touching a grounded metal object. Integrated circuits can be damaged by
electrostatic discharge, handling the circuit board by its edges and avoiding touching any
metal components on the board decreases the chances of electrostatic damage.
3.1.1 Electromagnetic Compatibility Considerations
The XDT has been designed and verified by testing to meet the requirements of the EC Council
EMC Directive 89/336/EEC, for Industrial, Scientific & Medical equipment. The sensor ground is
isolated from the AC ground, logic ground, 4-20mA loop return, etc.; however they are also
shunted with a 0.1uf capacitor 1M Ohm resistor, and a 33V Transient Voltage Suppressor; this
prevents electrostatic buildup, noise pick-up, and in conjunction with the internal fuse protects the
instrument from over-voltage inputs. Please consider the following electromagnetic interference
issues during installation:
• In order to provide an acceptable noise environment for the XDT or any other digital equip-
ment in the proximity of switched inductive loads, it is recommended that there be varistors
placed across the inductors to keep down the high voltage spikes during transitions.
• Any circuitry which is activated by relay contacts should account for the contact bounce, one
simple debouncing method is placing a capacitor across the relay contacts.
• AC power wiring should be routed as far away from the XDT and its wiring as practical.