Epson manual Instrument Precautions using the XDT, Electromagnetic Compatibility Considerations

Section 3: Instrument

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.

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