AI-Tek Instruments TACHTROL 3, Инструкция по эксплуатации, Страница: 29 / 30

FOR SCHEMATICS WRITE TO: SCHEMATICS
AI-Tek Instruments
152 Knotter Drive
P.O. Box 748
Cheshire, CT 06410-0748
INSTALLATION AND WIRING PRACTICES FOR ELECTRONIC INSTRUMENTATION & CONTROL
The following practices should be followed in the installation of electronic indicating and control
devices in industrial locations. Each installation will be different and generally more care should be
exercised as installations become wires that transmit frequencies or pulse coded data.
The following practices should be observed:
1. Locate equipment away from sources of water, humidity, heat or dust, or provide a suitable
enclosure to protect the equipment from these elements.
2. Locate equipment away from SCR’s. triacs, buzzers, horns, heavy motors, welding equipment,
contactors, heavy current relays or other electrical noise generating equipment.
3. Use a metal enclosure to protect the electronic components from radiated electrical noise or
other magnetic influences. If the electronic equipment is removed from its original cabinet, it
should only be installed in panels or cabinets with other low level electronic devices.
4. Conduits from low level signal and control wiring should be separate from wiring for switching and
power wiring. Cabinet and panel wiring should be planned so the power and relay wiring is
dressed to one side. and low level signals dressed to the other side. Wiring to barrier strips, con-
nectors and relay contacts should be planned also for maximum separation.
5. Signal and control wiring should be at a minimum run in twisted pairs. Lines for magnetic pickups,
pulse type outputs and other frequency devices should be run in separate 2 wire shielded cables.
6. The switching of balanced inputs (such as magnetic pickup inputs) should be accomplished by
switching both inputs. The switching of just one input creates an unbalanced line and introduces
additional electrical noise to low level signals.
7. The use of commutators or slip rings in transmitting low level signals is not recommended. Should
this practice be absolutely necessary, care must be exercised that the point of contact be main-
tained and clean at all times.
8. Shield Connections for shielded cables should be connected so that no current flows in the shield.
This is accomplished by connecting all of the shields in series. Care is exercised not to ground the
shield at any point. The shield is then connected to the instrument (tachometer or other device)
at the shield terminal. The case of the electronic instrument should be connected to earth ground.
Some instruments will provide a connection terminal for this purpose.
9. Provide a power line that is noise free and free of power interruption. Normally this will be a buss for
use by low power electronic devices. In some cases this may require constant voltage, isolation or
noise filters.
10. DC power busses should operate within the limits provided in the instrument’s specifications.
Special care to isolate DC relay contact wiring should be taken. Most electronic instruments will
not operate correctly on battery charger supplies unless the battery remains in the circuit. In
some cases removal of the battery with the charger remaining on may damage the instrument.
TROUBLESHOOTING
Most troubles wll be avoided by following the above practices. In particularly severe cases electri-
cal noise may be further reduced. As a general rule. electrical noise may be easily reduced at the
source. The installation of snubber networks or commercially available noise suppressors across relay
contact, relay coils and buzzers will usually be successful.
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