# PLC installation considerations

**URL:** <https://forumautomation.com/t/plc-installation-considerations/4486>\
**Category:** PLC (Programmable Logic Controllers)\
**Created:** [August 28, 2018, 5:12pm UTC](https://forumautomation.com/t/plc-installation-considerations/4486 "2018-08-28T17:12:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![sivaranjith](https://forumautomation.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@sivaranjith](https://forumautomation.com/u/sivaranjith)\
**Post date:** [August 28, 2018, 5:12pm UTC](https://forumautomation.com/t/plc-installation-considerations/4486/1 "2018-08-28T17:12:21Z")

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![image](https://cdn.forumautomation.com/original/2X/b/b5d306baf17c8570066f8a561f5c886683a8a2d8.jpg)

For a PLC installation, these are the factors that necessarily taken into account:

1. Environmental conditions of the physical environment where it will be located.
2. Distribution of components in the cabinet that will contain them.
3. Correct wiring and power.

### Environmental conditions of the physical environment where it will be located:

Normally-except express indication-, the environment where the [PLC](https://forumautomation.com/c/plc-programmable-logic-controllers) is located must be meet the following physical conditions:

- Absence of vibrations, blows, etc.

- Protection from direct exposure to sunlight or heat sources intense, as well as temperatures that exceed 50-60 degrees Celsius, approximately.

- Discard places where the temperature drops, at some point, through below 5 degrees Celsius or where sudden changes can give origin to condensations.

- Discard environments where relative humidity is below 20% or above 90%, approximately.

- Absence of dust and saline environments.

- Absence of corrosive gases.

- Environment free of flammable gases -for security reasons-.

- Avoid placing it next to high voltage lines, the distance being variable depending on the value of said tension.

## Distribution of components in the cabinet that will contain them.

It is the norm that the PLC is placed in a metal cabinet. Before choosing it, it has to know if this cabinet needs a built-in fan to force the ventilation of the air, because the ambient temperature exceeds the specified temperature, or to incorporate a heat generating element, if condensation problems are anticipated.

The cabinet is chosen in the right size so that it contains in a clear way not only the PLC but all the elements that are next to it, so that can perform a correct job in wiring and maintenance operations. The elements that are next to the PLC can be:

- switch or power switches,
- the corresponding protections,
- relays, contactors, etc.,
- power supplies,
- lint strips,
- cabling channels, etc.

The PLC can be placed in different positions; but, in general, it is situated vertically on DIN rail or perforated plate.

Regarding its distribution, the following considerations are taken into account:

- The heat dissipating elements -mainly the PLC and the sources of feeding- are located in the upper part of the cabinet, in order to facilitate dissipation of heat generated to the outside.

- Electromechanical elements - relays, contactors, etc. - are generators of magnetic fields due to their coils; Because of this, it is recommended Keep them away as much as possible. The transformers, meanwhile, will be located at the greatest possible distance from any part of the PLC.

## Correct wiring and power

For a correct wiring it is necessary to take into account some minimum rules, among the that are found:

- Separate the cables that conduct DC from the AC, to avoid interference.

- Separate the cables from the inputs of the outputs.

- If possible, separate the analog [**I / O**](https://forumautomation.com/t/plc-input-output-capabilities/2916) conductors from the digital ones.

- The power cables that feed contactors, power supplies, etc., run through a different channel of the I / O cables.

- The power and I / O cables run through a different tube or channel; it is recommended between both groups of cables a minimum distance of 30 cm, if they run parallel.

- Stable tension of the adequate value and exempt, as far as possible, from induced peaks by other devices of the installation.

- Protections against overloads and short circuits, by means of switches magneto-thermal, fuses, etc., as well as against grounding, for the middle of differential switches.

- Earth cable of the appropriate value and properly signalled by driver yellow green. If the installation does not have it, it is necessary to enable one, exclusively for PLCs, of -about- 3 to 5 ohms.