Micromod MOD: Modcell 2050R Users Guide Instrukcja Użytkownika Pobierz pdf (Strona 17)

IB-23C650

INSTALLATION

GROUND CONNECTIONS

The primary power ground system consists of the plant electrical ground

(equipment grounding conductors). AC ground and chassis ground are

connected when the termination housing is connected to the control module.

If this path is insufficient to dampen out noise spikes on the ac line, the

chassis ground may be connected directly to panel ground. The circuit

common for all signals is negative.

Electrical Noise

Electrical disturbances can be caused by lightning, motors and motor driven

devices, relays, solenoids, and communication equipment. These

disturbances often introduce electrical noise in power lines, transmission lines,

and site grounds. The successful operation of any microprocessor-based

device depends, in part, on the precautions taken to minimize the effect of

these disturbances. Often called "transients" or "voltage spikes", this form of

noise is infinitely variable in terms of amplitude, frequency, and duration.

Common sources of this type of noise are:

• loose or poor quality connections (especially power connections)

• arc welding equipment

• switches operating inductive loads

• relays, solenoids and other coil operated devices

• high current conductors – electric heater circuits

• fluorescent or neon lamps

• motors and motor driven devices

• switch mode devices – SCRs, thyristors

• lightning

• electrostatic discharges

Suggested Preventative Measures

Primary power circuit distribution system:

• Ideally, each microprocessor-based device should be provided with an

independent dedicated power source. Where this approach is not feasible

due to space availability or cost per device, an acceptable alternative is to

install constant voltage, isolation transformers in the branch circuit where

the microprocessor-based device is installed.

• In addition to the above, install a combination transient surge suppressor

and noise filter in the instrument side of the power distribution system.

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Micromod MOD: Modcell 2050R Users Guide Instrukcja Użytkownika Strona 17