Electrical substations: equipment to maintain and safety rules

In one line

Before maintaining any piece of equipment in a substation there are 5 golden rules for working de-energized that allow no shortcuts — here, electrical maintenance starts with safety, not the other way around.

What an electrical substation is

It is a facility designed to set the voltage levels of an electrical grid to make power transmission and distribution easier. They are classified as step-down (up to 13.2, 15, 20, 45 or 66 kV) and step-up (up to 132, 220, 400 kV or more).

Two basic relationships govern how they work: the electrical power carried by the grid is P = V × I, and the Joule-effect electrical losses are Loss = I² × R — the higher the transmission voltage for the same power, the lower the current and the lower the loss, which is the underlying reason step-up substations exist.

Its fundamental elements are three: transformers (the main equipment), switching elements (breakers, disconnect switches) and protection elements (fuses, automatic circuit breakers).

The 19 systems that need maintaining

The manual explicitly lists the equipment and systems that fall within a substation's maintenance scope:

1. Power transformers
2. Voltage transformers
3. Current transformers
4. Breakers
5. Disconnect switches
6. Fuses
7. Lightning arresters (surge arresters)
8. Reactors and capacitors
9. Measurement and control systems
10. Protection systems
11. Grounding systems
12. Bare aluminum and copper cables
13. Insulated power, force and control cables
14. Shielding system
15. 34.5/13.8 kV medium-voltage cells
16. Electrical installation and lighting system
17. Busbar system
18. The substation's auxiliary systems
19. Communications system

Seeing them listed together makes something clear: a substation is not just "the transformers" — maintenance covers everything from grounding to the facility's lighting.

General safety procedures

The manual is explicit that these procedures are fundamental to maintaining electrical equipment, not an optional appendix:

• Every electrical job must be backed by a work permit
• Every electrical job must be locked out and tagged according to a lockout/tagout instruction
• Only qualified, authorized personnel may work on an electrical installation
• Workers may not carry metal objects such as jewelry, bracelets, chains or other conductive items
• Use the appropriate personal protective equipment: dielectric helmet, protective gloves, etc.
• Wear work clothing with no conductive elements, made of fire-resistant materials
• Check that tools are in good condition before starting, and use dielectric tools
• Plan the job so that minimum clearance distances are kept under the worst-case conditions throughout
• Anyone who could touch a worker — directly or indirectly, with a tool or another object — must wear insulating boots and gloves
• During electrical storms, work must be stopped or not started, and personnel withdrawn until conditions improve
• Mark off the work area
• Do not use wet electrical equipment or work with wet hands
• Every electrical job must be carried out by at least two workers
• For live work, keep to the minimum approach distances

The 5 rules for working de-energized

When a job requires de-energizing part of the installation, the order of these five steps is not negotiable:

1. Effectively disconnect all sources of voltage
2. Lock out the switching or disconnecting devices, and install the corresponding tags
3. Verify the absence of voltage
4. Ground and short-circuit every possible source of voltage
5. Mark off the work area

Each step depends on the previous one having been done correctly: locking out before actually cutting off all sources, or assuming something is "de-energized" without checking it with an instrument, is exactly the kind of shortcut these five rules exist to eliminate.

What having this in writing is for

A safety procedure that only lives in the heads of the most experienced electricians gets lost when staff turns over. Having it as a fixed 5-step sequence, with the 19 systems of scope stated explicitly, turns electrical safety into a verifiable standard — you can audit whether it was followed, instead of just trusting that it was done "the way it's always done."

Benefits

• The list of 19 systems prevents the mistake of limiting maintenance to the transformers while neglecting grounding, protections or auxiliary systems
• The 5 rules for de-energized work are a universal electrical-safety procedure, applicable beyond this particular substation
• The basic formulas (P = V×I, Loss = I²×R) explain why step-up substations exist, not just what they are

Limitations to keep in mind

• The safety procedures listed are general — each country and company usually has its own regulations (NFPA 70E, local codes) that may require additional steps
• The list of 19 systems covers scope, not frequency: it does not say how often each one is checked, which depends on the specific equipment and its criticality
• No list of procedures replaces formal training in high-voltage electrical work — these are checkpoints, not a complete course

In summary

An electrical substation steps voltage up or down to transmit and distribute electricity, and its maintenance covers 19 different systems, not just the transformers. Before touching any of them, the general safety procedures and the 5 rules for de-energized work — disconnect, lock out, verify, ground, mark off — are the non-negotiable starting point.