RECOMMENDED FIRE PROTECTION MEASURES FOR SUBSTATION EQUIPMENT

Batteries

The hydrogen gas given off from batteries that are located in confined areas can, at certain concentrations, become an explosion hazard. Therefore, a continuously operating exhaust system should be installed when batteries are located in a room sized to contain only the battery(ies) or are located in a confined space where the buildup and retention of hydrogen gas could reach potentially explosive concentrations. 

The entrance door(s) to a battery room should have a "No Smoking" or "No Open Flame" warning sign posted on it. Lighting switches should be located outside of the room. All codes should be followed concerning the type of lighting fixtures, wiring, and installation of eye-wash stations. Precautions should also be taken to assure that the acid fumes will not be present in a concentration sufficient to cause damage to nearby relay contacts.

Surge arresters

Surge arresters should be properly sized and located to minimize the possibility of an equipment fire initiated from surges.

Direct-stroke lightning

If needed, direct-stroke lightning protection, e.g., grounded lightning masts, static wires, etc., should be installed so that all equipment and buildings are protected. Guidance in the installation of this protection can be found in ANSI/ NFPA 780-1992 [B30].

Grounding

All equipment in the substation should be properly grounded with correctly sized grounding conductors and proper terminations to dissipate fault currents. This is necessary to prevent failure of the grounding conductor or termination, which could result in more severe equipment damage and an associated fire. Guidance in grounding equipment can be found in IEEE Std 80-1986 [B45].

Fault-sensing and interrupting devices

The proper relaying or fault-sensing devices in combination with an interrupting device should protect all circuits and equipment. The combination of the devices used should operate and isolate the fault before any further and more serious problems could occur.

Metal-clad switchgear

Consideration should be given to the installation of a fixed extinguishing system for the protection of metal-clad switchgear that contains oil-filled equipment. Consideration should be given to the installation of smoke detectors on the ceiling of the switchgear room above the switchgear lineups. For guidance, see FM Data Sheet 5-19 [B41].

Oil-filled reactors

Consideration should be given to the installation of a fixed extinguishing system for the protection of oil-filled reactors. If the reactor(s) is enclosed in a sound-reducing housing, the fixed fire-extinguishing system should be installed both inside and outside the housing.

Power capacitors

Power capacitor units located outdoors, which contain a combustible dielectric fluid, should be a minimum of 10 ft (3.0 m) from any building not of fire-resistive construction. Capacitor units located indoors, which contain a flammable dielectric fluid, should be separated from adjacent areas by a 1 h fire-rated barrier.

Diesel or gasoline engines

A substation may contain diesel-, propane-, or gasoline-powered engines for fire pumps or standby electrical power. Installation of these engines should conform to ANSI/NFPA 37-1994 [B19]. Electrical apparatus on engines and generators should be fully spark-protected. For design requirements for propane fuel use, see ANSI/NFPA 58-1995 [B20].

Fuel-handling systems

Substation fuel-handling systems should conform to ANSI/NFPA 30-1993 [B18]. Buried tanks and piping should be corrosion-protected, and loading points for fuel should be located at the perimeter of the substation. Underground tanks should be located in a clearly marked area and should not be subjected to vehicle loads.

Relay and control panels

Panels should be designed and constructed to meet the recommendations for flame retardance contained in IEEE Std 420-1982 [B48].

Gas-insulated components

Consideration should be given to the control of SF6 gas and the mitigation of gas by-products that may be generated as either a direct or indirect result of fire. Precautions regarding the harmful effects of SF6 gas and SF6 gas by-products are given in IEEE Std C37.122-1993 [B43] and IEEE Std C37.122.1-1993 [B44].

High-pressure oil-filled-cable pumping plants

Consideration should be given to the installation of a fixed extinguishing system for the protection of oil-filled-cable pumping plants and storage tanks.