TRANSMISSION AND DISTRIBUTION SUBSTATIONS

Transcription

1 A.U.C. 338, ADDENDUM 2 October 20, INTRODUCTION 1.1 Transmission Substations receive 345,000 volts from generating stations and then step it down to 138,000 volts for delivery to Distribution Substations. Here the electricity is stepped down for delivery to the utilities various overhead and underground networks. Network Brooklyn & Queens Manhattan & Bronx Staten Island Voltage Received 27,000 V 13,000 V 13,000 V and some 33,000 V Table 1 Note: Some substations are architecturally designed to mimic surrounding building styles and may not be immediately recognizable as substations. (Photo 1) Photo 1 Con Edison 1

2 Borough AREAS SERVED BY ELECTRIC UTILITIES Brooklyn, Manhattan, Bronx, Staten Island, Most of Queens Utility Company Con-Edison Broad Channel, Rockaway Queens LIPA Table 2 2. SUBSTATION HAZARDS 2.1 High Voltages - Voltages as high as 345,000 volts can be found at these locations. 2.2 Exposed Electrical Bus - 3 aluminum bus, looking like metal conduit, runs overhead in these locations. The bus is mounted a safe distance above the ground. The distance is determined by the voltage it carries. (See Table 3) High voltages are carried on the outside skin of this bus and anything or anyone encroaching upon the safe distance can attract a high voltage arc from the bus. (Photo 2) Photo 2 Exposed overhead electrical bus carries a high voltage electrical charge on its exterior surface Voltage Safe Distance 345,000V 18 feet 15,000V to 38,000V 10 feet Table 3 2

3 2.3 Capacitor Banks - (Photo 3) Capacitor Banks are found in locked caged-in areas. The exposed electrical contacts pose an electrocution hazard. Even after power has been removed, capacitors retain a potentially deadly electrical charge. Photo 3 Capacitor banks are enclosed by fencing to prevent contact with exposed electrical conductors 2.4 Battery Rooms - (Photo 4) Transmission and distribution substations typically have two battery rooms, each containing as many as 60 car-type batteries. These banks of batteries can be found in locked rooms connected in series, creating a 125V DC back-up system for the substation. A warning sign will be posted on the locked door. Photo 4 Substation Battery Room 3

4 2.5 Transformers - (Photo 5) These large transformers have a 20,000-60,000 gallon oil capacity and either boost or reduce the voltage of incoming and outgoing electricity. Exposed electrical contacts and high voltages can pose a significant threat to firefighters. Photo 5 Substation Transformer 3. SUBSTATION CHEMICAL HAZARDS 3.1 Polychlorinated Biphenyl (PCB) - PCBs were in insulating oil used in transformers and capacitors prior to 1977 and can still be found in some transformers and in the paint used on older transformers. a) Con Edison has removed PCBs from the system by retro filling transformers with non-contaminated oil. Some areas of these transformers cannot be retro filled or tested and may still contain PCBs. b) Treat all transformer incidents as PCB incidents. Smoke, spilled oil and water runoff from transformer fires may be contaminated with PCBs. 3.2 Edisol XT is viscous insulating oil currently used in capacitor banks. PCB containing capacitor banks have been removed from the system but as a precaution, treat all capacitor fires as PCB incidents. Dermal exposure to the oil results in skin irritation. 3.3 Dielectric Fluid - This non-pcb insulating oil, resembling cooking oil, is used to cool underground transmission lines. The oil is pumped under pressure through feeder lines which are buried in some places as shallow as 2½ feet below the surface. a) Because there are no section valves on the feeder lines, leaking oil can result in a large oil spill. An underground leak may result in oil seeping up from the ground. These electrical feeder lines carry 345kV. (Photos 6 and 7) 4

5 Photo 6 Photo 7 Cut-away of oil filled underground Exposed 345KV underground 345kV feeder line feeder lines 3.4 Sulfuric Acid - The led/acid batteries found in the substation s battery room contain 5 to 10 gallons of 30% to 40% acid. The acid is corrosive, and heat from a fire can vaporize the acid resulting in a sulfuric acid mist that may be deadly if inhaled. In addition, hydrogen is generated by the charging batteries. 3.5 Sulfur Hexafluoride Gas (SF6) - This colorless, odorless gas is used to insulate and extinguish arcs in electrical equipment, and is five times heavier than air. In sufficient quantities, it presents an asphyxiation hazard in confined areas and below grade spaces. In some stations, tanks of this gas are stored in dedicated storage rooms or outdoors in banks of cylinders. (Photo 8) a. Thermal decomposition of SF6 gas produces: 1) Hydrogen Fluoride (HF) - This gas has a strong irritating odor similar to rotten eggs. Prolonged exposure to HF gas will desensitize your sense of smell making it undetectable. Inhaling HF gas can result in immediate or delayed onset pulmonary edema. 2) Metal Fluoride powder - This white powder is a byproduct of thermal decomposition of SF6 gas and is extremely corrosive to bare skin. The initial sign of exposure would be reddening of the skin. Skin contact and inhalation must be avoided. 5

6 Photo 8 Circuit breakers containing SF6 gas 4. INCIDENT RESPONSE 4.1 Respond to the designated muster site. (See AUC 338 Add. 1) 4.2 Meet and consult with the Con Edison White Hat at the muster site. Have White Hat retrieve information from the Lockbox located inside the substation. The Lockbox contains information that can be useful to the Incident Commander including PCB information, overhead photo, a site diagram and list of the hazards present at the substation. (Photos 9 and 10) 4.3 Some substations are staffed 24 hours a day. However, if a White Hat is not on scene, call the posted number and request that one respond. Photo 9 Photo 10 White Hat Decal at muster site Lockbox is located inside the substation. 6

7 5. FIRE RESPONSE 5.1 Set up handlines and/or large caliber streams to protect exposed buildings around the substation. Do not direct water into the substation or put water onto electrical equipment unless requested by the Con Edison White Hat. Note: Water application onto or in the vicinity of live electrical equipment will be as per AUC A 3½ supply line shall be stretched, but not charged, to the sprinkler siamese if present. If requested by Con Edison White Hat, supply the siamese with water at the posted pressure. Sprinklers if present protect only the transformers. (Photo 11) Photo 11 A siamese fitting located on the outside wall of a substation 5.3 Transformer fire - A transformer fire is an oil fire. The burning oil will be difficult to extinguish because the transformer shell will act as a barrier and shield the fire from water or foam application. 5.4 Capacitor Bank Fire - These are usually small and often are extinguished by substation personnel before our arrival. Small fires can be extinguished with a dry chemical extinguisher. 5.5 Battery Room Fire - Carbon dioxide should not be used as an extinguishing agent at these fires. The plastic battery shell may crack when cold CO2 gas is applied to the fire causing sulfuric acid to spill out and be vaporized by the heat. This creates a respiratory hazard as the acid in the batteries is very corrosive. Dry chemical extinguishers will work here as will water application from a safe distance. 7

8 6. GENERAL PRECAUTIONS Caution and cooperation with the Con Edison White Hat will enable us to safely mitigate emergencies and fires at Con Edison Substations. It is essential that the Incident Commander and company officers maintain strict control of personnel because of the hazards found in substations. Do not force entry into a substation. Wait for the White Hat. All chemical and electrical hazards are placarded with warning signs. Take note of these signs and heed the warnings. (Photo 12) Do not cut fences or force open locked doors or gates. Inside substations, ground level electrical hazards are fenced-in or kept behind locked doors and gates. Do not climb. High voltage conductors are located overhead. Any violation of safe distances puts members at risk of electrocution. Avoid bringing metal tools into the substation and do not allow any tools to project above your shoulder. Also, wood or fiberglass hooks can conduct high voltages found in substations. Always assume that water runoff and smoke is contaminated with PCBs and operate accordingly. Operate uphill and upwind when possible. Keep firefighters and civilians out of the spilled oil, water runoff and smoke from firefighting operations. When raising aerial ladders and tower ladder buckets, maintain an 18-foot safe clearance horizontally from the substation s exterior fence line and do not place portable ladders, aerial ladders or tower ladder booms or buckets against or over the wall or fence. The application of water onto or in the vicinity of live high voltage electrical equipment should not be attempted except as per AUC 338. Wear full PPE to protect from potential dermal and respiratory hazards. SCBAs shall be used even in a light smoke condition due to the potential for PCB contamination. Always operate as if PCBs are present. Consider decontamination when exposed to smoke, oil or possibly contaminated water run-off. Always consult with the White Hat on hazards, safety and proposed tactics. Photo 12 Be alert to your surroundings and note hazard signs 8

9 Note: There are a number of independent substations in New York City that are not under the control of Con Edison. These independent substations have the same hazards as Con Edison, and the same precautions apply. They may not have a White Hat program in effect. Battalion Chiefs should initiate contact with personnel at these independent substations, learn their operating procedures and develop procedures that will ensure safe operations. All Con Edison substations have been entered into the CIDS program. independent substations shall also be entered into the CIDS program. When discovered, 9