Cable operability refers to the basic function of electrical cable within a power plant: to transmit control signals, instrument signals and electrical power. In most non-nuclear power plant sites, cables aren’t required to function in adverse conditions. This means that these cables should be able to conduct signals or power while maintaining reasonable insulation characteristics – in other words, they should function without shorting or signal attenuation.
However, certain cables (especially those related to safety applications) may need to function while exposed to harsh or adverse environmental conditions. For these cables, operability means being able to function during normal conditions while also maintaining the ability to operate to a satisfactory level during emergency issues (such as a loss of heating and cooling controls in a power plant scenario).
For cable operability, electrical cable needs to be better insulated and protected than standard HVAC electrical cable, or the type of cable used in air condition repair for example.
Concerns raised
In recent years, operability concerns have been raised regarding low-voltage cable in power plants which could potentially be exposed to accidents. Issues included the use of excessive lengths of unsupported cable drops, the reduced bending radius of cable after installation, impact damage to cable during installation, the addition of cable to occupied raceways which could damage existing cable, and other associated handling/installation concerns.
Cable operability checklist
To ensure cable operability in a power plant, it is advisable to adhere to the following:
- Consider the applications of the cable: is your cable of choice fit for purpose? Is the insulation sufficient to protect it?
- Keep a record of cable performance: if a cable has failed, note why it has failed to avoid encountering the same problem again.
- Environmental qualification: is the cable sufficiently shielded and of a quality to function in extreme weather conditions?
- Practical installation: can the cable be practically and safely installed without damage?
- Voltage differences: differences in low-voltage power, medium-voltage power, and cable stresses during use should inform your choice of cable.
- Regular testing: can you routinely perform in-situ testing for suspect installations and the general monitoring of cable condition?
- Operating voltage vs rated voltage: have you considered this to avoid a blowout?
- Safety function vs intrinsic capability: is the cable sufficient to function above capacity in the event of an emergency, for example?
- Cable support in accident conditions: will the cable ensure connected devices remain functional during an accident scenario?
By following these guidelines, engineers can ensure cable operability in power plants. However, it’s worth noting that these basic principles can also be applied to ensure maximum cable operability in all manner of engineering tasks. For example, a plumber connecting a pipe trace cable or an air condition repair engineer performing maintenance work may be able to increase longevity by adhering to these simple principles.
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