Thermo Scientific APEX 100, Руководство пользователя

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Thermo Scientific APEX User’s Guide
Page 283
Electrical Set-Up
All wiring, except as noted, is the responsibility of the customer. Detailed below are the
general electrical requirements and the types of supply voltage and connections needed
when installing your APEX detector. Please follow these requirements carefully—for your
own personal safety and the safety of others. In the following instructions, the acronym
“PSU” refers to the detector’s power supply unit, “PCB” refers to a printed circuit-board,
and “PCB–A” refers to a printed circuit board assembly.
Potential Causes of Interference
The detector is a balanced alternating-current magnetic sensor, and—as a result—is
subject to interference from a variety of external mechanical, electrical, and magnetic
sources. These potential sources of interference are described in more detail below.
Mechanical Vibration
Mechanical vibration induces alternating-current eddy patterns in the detector’s metal
case, which may interfere with the detector’s X-channel. If the vibration is severe, the
R-channel may also be affected.
Electro-Magnetic Induction
When electro-magnetic currents are induced in external hardware and cables, this may
cause three types of interference, as follows.
• “Dirty” Power Lines
This type of interference may occur when several pieces of equipment are
connected to the same power line. In most cases, variable-frequency drive
motors are the culprits. In general, any equipment that utilizes switching
technology is a potential source of contamination. Both the X- and R-channel
may be affected.
• Magnetic Fields Caused by High Currents in Wires and Cables (Near-Fields)
When high electrical currents pass through wires and cables they create magnetic
fields, known as “near-fields.” These near-fields may interfere with the detector’s
X- and R-channels, especially when high-current cables lie in close proximity to
the detector.
• Electromagnetic Waves
This source of interference is less common, but is still a valid concern—especially
when the external wave interferes with a vital internal frequency in the detector’s
circuitry. Both the X- and R-channel may be affected.
Alternating Conducting Loops
Alternating conducting loops (known as “loop effects”) may create noise in the detector.
A loop effect may be created when a conductive path that varies in time, lies in close
proximity to the detector. When a loop effect is created, the X-channel is the one most
likely to be affected.