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