Emergency Power Systems 101 An Overview of Emergency Power Systems Craig Ayers, MHA, CHFM, CHSP, CPO
Emergency Power Systems Purpose Generators Distribution Transfer switches Maintenance and testing Contingency planning
Generator Indoor Indoor units Parallel Units
Generators Outdoor Day tank No day tank
Generators Starters Battery start type starters
Generators Batteries Batteries (maintenance free and conventional). Test batteries by using specific gravity or load testing. Usually the weakest link with generator failure. Keep clean and frequently check for corrosion. Replace every couple of years.
Generators Battery Chargers Float chargers Make sure operates properly Should be on life safety branch
Generators Starters Air start generators uses air pressure to turn starter.
Generators Starters Air compressor setup for air start generator Compressed air storage tank (enough for two starting cycles) Electric motor on emergency power. Gasoline power motor for backup.
Generators Jacket Heaters Jacket heaters keep the generator warm for quick starts. Heaters can sometimes have a high failure rate as elements tend to burn our over time. Can be easily checked by touching the engine (90-110 degrees) Multimeter can be used to troubleshoot.
Generators Jacket Heaters Diesel engines were originally designed for vehicles. In this application, they are equipped with a starting aid (glow plugs or ether). Operating manuals for diesel vehicles recommend the engines be allowed to idle until warm. This warm-up period is needed to allow dissimilar metals in the engine to expand to proper operating tolerances. Unlike a vehicle, when there is a power failure, there is no opportunity to warm-up: it needs to carry a load immediately. Thus almost all emergency diesel generators are installed with inexpensive resistance heaters to maintain the generator at a consistently warm temperature. This is needed to insure a safe and reliable split-second start-up, and to prevent 'cold start wear.' Depending on the size and environment of the emergency diesel generator, more than one resistance heater may be needed. In engines with two resistance heaters, one heater usually carries more of the load, running longer than the second heater. Factory specifications typically recommend that heaters engage at 90 F and turn off at 110 F. Installation specifics such as engine location, make, and model effect starting characteristics, so the optimal temperature range may vary, however there is no redundancy built in these systems (GTS, 2007)
Generators Fuel Storage and Distribution Above ground. Below ground. Can serve single or multiple generators. Size and location are considerations when designing fuel storage systems. Must meet EPA standards.
Generators Fuel Transfer Pumps Flow indicator Pumps should be on the life safety branch. Should be checked for operation on a routine basis. Location of pumps should be considered when designing systems. Redundant pumps for backup operation.
Pump controls can be stand alone with on/off status and controls.
Generators Distribution Systems Pump controls can be a combination of controls and alarms for pumps and fuel tank management. Main tank fuel supply Pump status
Generators Parallel Setup What is it? Connecting two or more generator sets together on a single distribution circuit. Generators voltage and frequency must be synced together using paralleling gear. Similar to utility company generator arrangements. Newer technologies using data connections make paralleling generators.
Generators Parallel Setup ASCO,
Generators Paralleling Gear Medium voltage paralleling gear.
Generators Parallel Setup The easiest way to setup a parallel system is to use generators that are exactly alike, or at least have the same output rating and alternator pitch. Another flexible approach to backing up your power requirements is to have two or more generators of variable output. In either scenario, these can be connected in parallel with paralleling switchgear to achieve maximum output during peak requirement or the desired minimal output during other times (Diesel Service, 2013)
Generators Parallel Setup Benefits of parallel generators Reliability Expandability Flexibility Ease of Maintenance Cost effectiveness and Quality Performance
Distribution Typical Utility Power Generator Transfer Switches
Transfer Switches Transfer switches are used to switch electrical loads from utility power sources to generator power sources. Transfer switches may be isolation bypass type, open transition, or closed transition type. Three or four pole Manual or automatic Phase monitoring May have built in exercise timers or battery chargers built in the switch.
Transfer Switches Basic Basic transfer switch with no isolation bypass. Test switch and switch position indicators. Some may have retransfer switch.
Transfer Switches Isolation Bypass
Transfer Switches Isolation Bypass Isolation bypass switches provide a means to isolate the switch in order to provide maintenance while maintaining power to the load. Higher cost Larger design Bypass still requires periodic servicing.
Transfer Switches Open Transition Most basic for small load profiles (most common) Short interruption when transferring. Delayed Transition For medium and large load profiles Longer interruption to let magnetic fields collapse on motors before transferring load. Closed Transition (make before break) Generator and utility power are connected when synchronized, then load shifts to generator. Can be used to avoid power disruptions during transfer. Used in life safety and critical processing loads.
Transfer Switches Open Transition Open transition transfer switches are designed to switch between the normally present power supply; which is being supplied to our homes by the power stations, and the backup arrangement in the form of some generator or anything. They operate between these two supplies depending upon the conditions, if the primary power supply is available or not. They have a switch which monitors the power sources and keeps a check so that whenever the primary source fails to deliver the power, it immediately switches to the backup set of generators. But the major difference that it has from the closed transition transfer switch is that, this switching is not performed immediately, instead there is a short break between the opening of one contact and the closing of the other (EEC, 2013)
Transfer Switches Closed Transition A closed transition transfer switch also operates on the same principle as that of an open transition switch, except the fact that the delay which is incorporated in the open transition switch has been eliminated and hence the contacts occur without any delay in the time (EEC, 2013)
Transfer Switches Timing General Time Setting (basic) When to start generator after power is off. After generator start and comes up to speed, when to transfer. When utility power restores, how long to retransfer back to utility power. How long to keep generator running (cool down time). Generator starting circuit will usually daisy chain to several transfer switches.
Transfer Switches Testing and Servicing Must be operation once a month (12 times per year). Test switch is an acceptable method of simulating a power failure. It interrupts power to the power sensing board. Consider opening breaker occasionally. Should be inspected and services at regular intervals. Rotate the transfer switch use for starting each month. Have someone at the generator when testing switches to verify a good generator start.
Distribution Typical Utility Power Generator Electrical Branches
Distribution Life Safety Branch Means of egress lighting Exit signs Fire alarms Medical gas alarms Mechanical, control, or other accessories required for effective life safety Communication systems (such as paging) Battery charger for task lighting at generator set Generator accessories battery charger/fuel systems Elevator lighting, controls, communication, and signals Automatic doors used for egress (NFPA 70)
Distribution Critical Branch Power for task illumination, selected receptacles, and fixed equipment in following areas: Infant nurseries Medication preparation areas Pharmacy dispensing areas Selected acute areas Psychiatric bed areas (omit receptacles) Ward treatment rooms Nurses stations Other patient care areas where needed (NFPA 70)
Distribution Critical Branch General care patient beds (at least one receptacle) Angiographic labs Cardiac catheterization labs Coronary care units Hemodialysis rooms or areas Emergency room treatment areas (selected) Human physiology labs Intensive care units Postoperative recovery rooms (selected) (NFPA 70)
Distribution Critical Branch Other areas and systems Nurse call systems Blood, bone, and tissue banks Telephone and data equipment
Distribution Equipment Branch (Delayed Connection) Vacuum systems Sump pumps Compressed air systems (medical and control) Smoke control and pressurization systems Kitchen hood systems HVAC/exhaust for isolation rooms, protective environment rooms laboratory, pharmacy, nuclear medicine, ETO, operating and delivery rooms, and telephone and data rooms Heating equipment (NFPA 70)
Testing and Maintenance Load Testing The monthly tests for diesel-powered emergency generators are conducted with a dynamic load that is at least 30% of the nameplate rating of the generator or meets the manufacturer s recommended prime movers exhaust gas temperature. If the hospital does not meet either the 30% of nameplate rating or the recommended exhaust gas temperature during any test in EC.02.05.07, EP 4, then it must test the emergency generator once every 12 months using supplemental (dynamic or static) loads of 25% of nameplate rating for 30 minutes, followed by 50% of nameplate rating for 30 minutes, followed by 75% of nameplate rating for 60 minutes, for a total of 2 continuous hours. Note: Tests for non diesel-powered generators need only be conducted with available load. (EC 02.05.07 EP5)
Testing and Maintenance Load Testing At least once every 36 months, hospitals with a generator providing emergency power for the services listed in EC.02.05.03, EPs 5 and 6, test each emergency generator for a minimum of 4 continuous hours. The completion date of the tests is documented (EC 02.05.07 EP7)
Testing and Maintenance Load Testing Annual 25% load for 30 minutes, then 50% load for 30 minutes, then 75% load for 60 minutes 36 Month 30% for 4 continuous hours You can combine the two tests but you must meet the 30% minimal load.
Testing and Maintenance Fuel Checking a generator s fuel delivery system periodically is an important aspect of generator maintenance. Common problems with generators are: Stored diesel fuel will deteriorate over time Sludge and water will accumulate on the bottom of the tank, and rust can form on the sides Bacteria and fungus can grow in the fuel itself (ESP, 2015) Beware of biofuels, they deteriorate quickly Consider annual fuel cleaning service
Testing and Maintenance Engine Oil Engine oil testing can determine the health of your engine and can predict failure in engine components. Antifreeze testing can determine the condition of the coolant and helps in preventing corrosion. Important to maintain coolant integrity.
Testing and Maintenance Annual maintenance and load testing takes your generator out of service for possible power outages. Consider doing annual maintenance and load testing at the same time while utilizing a portable standby generator for emergencies.
Contingency Planning Quick connect hook ups for portable generators make it easy for testing and provides a quick method for connection of portable generators. Quick connect box Transfer switch
Contingency Planning Quick connect used with hypalon generator cables
Contingency Planning Portable generators can supply power in the event of generator failure. Providing electrical connections for scheduled maintenance and unscheduled outages makes the use of portable standby generators more proficient.
Questions
References Diesel Service (2013). Parallel Operation of Generator Sets: Diesel Service and Supply. Retrieved March 2, 2016 from: http://www.dieselserviceandsupply.com/parallel_gensets.aspx EEC (2013). Electrical Installation and Energy Efficiency: Electrical Engineering Community. Retrieved March 1, 2016 from; http://engineering.electrical-equipment.org/panel-building/closed-transition-transfer-switch.html EEC (2013). Electrical Installation and Energy Efficiency: Electrical Engineering Community. Retrieved March 1, 2016 from; http://engineering.electrical-equipment.org/panel-building/open-transition-transfer-switch.html ESP (2015). Fuel Testing: ESP Generators. Retrieved March 3, from http://espgenerators.com/fuel-testing/ GTS (2007). Heating Emergency Diesel Generators: Geothermal Systems. Retrieved March 21, 2016 from: http://gtsheaters.com/gts_white-paper_v3-3.pdf NFPA 70 (2014) National Electric Code