Emergency Power Systems Scott Thomas Director - Application - - PowerPoint PPT Presentation

▶
emergency power systems
SMART_READER_LITE
LIVE PREVIEW

Emergency Power Systems Scott Thomas Director - Application - - PowerPoint PPT Presentation

Jul 13, 2023 452 likes •1.01k views

Emergency Power Systems Scott Thomas Director - Application Engineering Cummins Southern Plains Agenda Generator Application Considerations Ratings Diesel vs Natural Gas Common Design Challenges Packaging Enclosures and

slide-1
SLIDE 1

Emergency Power Systems

Scott Thomas Director - Application Engineering Cummins Southern Plains

slide-2
SLIDE 2

Agenda

  • Generator Application Considerations

– Ratings – Diesel vs Natural Gas – Common Design Challenges

  • Packaging – Enclosures and Fuel Tanks

– Emissions – Common Generator Failures – Maintenance Recommendations

  • Automatic Transfer Switches

– Basic Functionality – Open and Closed Transition – ATS Types

  • Question and Answer
slide-3
SLIDE 3

Generator Ratings

slide-4
SLIDE 4
  • ISO 8528-1 Sect. 13 defines these ratings:
  • Emergency Standby power (ESP)
  • Limited Time Prime Power (LTP)
  • Unlimited Time Prime Power (PRP)
  • Continuous Operating Power (COP)
  • Any manufacturer can go above and beyond

the ISO ratings definitions

Definitions

slide-5
SLIDE 5

Standby rating 2750 kW Max avg. load in 24h period (70%): 1925 kW 200h/year Unlimited Time Prime Power Rating 2500 kW Max avg. load in 24h period (70%): 1750 kW Unlimited Hours with Variable Load Limited Time Prime Power 2500 kW Max load is (100%): 2500 kW 500h/year with constant load Continuous Operating Power 2100 kW Max load is (100%): 2100 kW Unlimited Hours with Constant Load

Rating Example 2750kW DQLF

slide-6
SLIDE 6

Fuel Selection

Diesel Generators

  • Local Fuel Source
  • Better Transient Response
  • Lower Cost >150 kW

Natural Gas Generators

  • Unlimited Fuel Source – Outage Risk?
  • Slight Cost advantage <150 kW
  • Larger Footprint >150 kW
  • Emissions
slide-7
SLIDE 7

Common Design Challenges

  • Sound – Contact city to verify sound requirement at property line
  • Fuel Tanks – Contact Fire Marshall for fuel storage requirements
  • Clearances

– Recirculation of radiator discharge air – Proximity to ATS - Transformer

  • Natural gas supply piping
  • Generator Sizing

– Fire Pumps – WWTP/LS/PS – VFD’s - Harmonics

Cummins Confidential

slide-8
SLIDE 8

Sound Attenuation

slide-9
SLIDE 9

Sources of Sound

– Engine noise

  • 100 -110dB(A)@1m

– Cooling fan noise

  • 100-105dB(A)@1m

– Alternator noise

  • 80 – 90dB(A)@1m

– Structural/mechanical noise

  • Vibration, Gears etc.

– Un-silenced engine exhaust

  • 120-130dB(A)@1m
slide-10
SLIDE 10
  • Contact City to understand local requirement based on zoning
  • f property – field testing requirements.
  • Increase distance from receiver (Property Line)

– Sound pressure drops ~6 dBA at 2x distance

  • Insert high mass, absorptive barriers – Enclosure Baffles
  • Watch for reflective surfaces

– Perceived sound pressure increases 3dBA due to a reflective surface; 5dBA for two reflective surfaces

  • Direct noise away from sensitive locations

– Radiator discharge turning vanes (Scoop) – Engine Exhaust elbows

Sound Attenuation Strategies

slide-11
SLIDE 11

Sound Attenuation Strategies

slide-12
SLIDE 12

Sound Attenuation Strategies

slide-13
SLIDE 13

Installation Review: Airflow Restriction

slide-14
SLIDE 14

Installation Review: Airflow Restriction

slide-15
SLIDE 15

Installation Review: Airflow Restriction

slide-16
SLIDE 16
slide-17
SLIDE 17
slide-18
SLIDE 18
slide-19
SLIDE 19
slide-20
SLIDE 20
slide-21
SLIDE 21

Installation Review: Accessibility

slide-22
SLIDE 22
  • Ease of Access

– Fuel Fill – Load Bank Connections

  • Weather Events

– Snow Loading / Plowing – Flood Plain

  • Proximity to Occupied Facilities

– Windows/Doors – Ventilation Intakes

Location Considerations: Outdoor

slide-23
SLIDE 23

Location Considerations: Indoor

  • Safety

– Dedicated space – Working space (36” or 1 m minimum) – Working height

  • Future Planning

– Additional equipment space – Future genset capacity – Replacement parts access

slide-24
SLIDE 24

Diesel Fuel Systems

slide-25
SLIDE 25
  • Tank size

– Contact Fire Marshall for volume, tank construction expectations, and field testing requirements – Access and filling for rooftop installations – Actual run time required/desired

  • Fuel temperature concerns

– Cold - Waxing point of particular diesel blend on-site – Warm – Fuel return temperature in small tanks

  • Tank ventilation (Discharge to exterior)
  • Special requirements for onsite testing, alarms,

remote fill stations

Diesel Fuel Tanks

slide-26
SLIDE 26

Diesel Fuel Tank Notes

  • UL 142 and UL 2085 listing requires pressure/leak testing

prior to shipment

  • Common Options:

– Overfill protection valves (OFPV) – Spillboxes – Fuel level alarms – Polishing systems – Remote Fill Stations – Elevated Vents

  • Be weary of additional control/breaker handle height with

subbase tanks

slide-27
SLIDE 27

Day Tank Notes

  • 2 to 4 hour run time
  • One day tank for each generator set
  • As close to the generator set as possible
  • Automatic filling control
  • Ability to return fuel back to bulk tank

– Auxiliary pump or gravity return

  • Manual filling provision

Options:

– Utilize genset subbase tank with additional ports – Standalone day tank from 3rd party supplier

slide-28
SLIDE 28
  • Size Lines for Flow, NOT Consumption
  • Route for Lowest Restriction

– Limit fittings, bends, and length of runs

Diesel Fuel System Piping

slide-29
SLIDE 29

EPA Emissions Tables

slide-30
SLIDE 30
  • CI NSPS Stationary Emissions - Diesel engines
slide-31
SLIDE 31

EPA SI NSPS Final Rule

slide-32
SLIDE 32

Stationary Emergency Engine Designated Use for NSPS and RICE NESHAP

  • Unlimited use during emergencies

– Utility failure, transformer, UPS, circuit breaker, ATS – Document issue as a part of record keeping requirement

  • 100 hours per year allowed for:

– Maintenance and testing – Emergency Demand Response (EDR) programs (May 1st 2016 EDR Revision) – 50 hrs/year (of the 100hrs/yr) for non-emergency

  • peration allowed (if there is no financial

arrangement*)

  • e.g.: storm avoidance
slide-33
SLIDE 33

Generator Maintenance

slide-34
SLIDE 34

Common Generator Failures

– Dead Batteries (Redundant Battery String & BBS) – Battery Charger Failure (Redundant Battery String & BBS) – Fuel Quality (Fuel Filtration Systems, Fuel Maintenance Program) – Low Coolant Levels (Periodic Inspection – Alarm) – Control not in Auto (Remote Annunciator – SCADA Alarm) – Circuit Breaker Open (Remote Annunciator – SCADA Alarm)

slide-35
SLIDE 35

Maintenance Recommendations

  • Cummins recommendations for Annual Maintenance

– Quarterly Inspections – Annual Oil/Filter Change – Annual Supplemental Load Bank Testing

  • In addition to any building load tests throughout the year.

– Battery Replacement

  • Per NFPA 110, batteries to be replaced in standby generator sets every two

years.

– Annual Fluid Sampling

  • Fuel/Oil/Coolant Analysis

– ATS Inspections

  • Operate with load at least once per year
slide-36
SLIDE 36
  • A device that transfers

electrical loads between two sources of power by using either automatic or manual controls

  • ATS monitors utility voltage

and frequency

  • On utility failure generator

starts and accelerates to rated speed and voltage

  • ATS senses source available
  • Time delay on transfer

What is a Transfer Switch?

  • Utility
  • Transfer

switch

  • Generator
slide-37
SLIDE 37

Transition Types and Applications

  • Open Transition (In Phase or Time delayed /

Programmed Transfer)

  • Closed Transition
slide-38
SLIDE 38
  • To Loads
  • !
  • From
  • Utility

Open Transition – Utility to Genset

Utility Power Fails Generator Starts Gen Source Available Load Transfers to Generator

slide-39
SLIDE 39
  • !
  • From
  • Utility
  • To Loads

Open Transition – Genset to Utility

Utility Power Returns ATS retransfers load to Utility ATS removes gen run command

slide-40
SLIDE 40

From Utility To Loads Load (Residual) Voltage Utility/Genset Voltage

Time Delayed Transition

slide-41
SLIDE 41

INDUCTIVE LOAD UTILITY UTILITY UTILITY LOAD VOLTAGE

Pre-determined delay allows the residual voltage to decay

TIME INDUCTIVE LOAD INDUCTIVE LOAD

Time Delayed Transition

slide-42
SLIDE 42

Closed Transition

From Utility To Loads

slide-43
SLIDE 43

LOAD UTILITY LOAD UTILITY LOAD UTILITY TIME LOAD VOLTAGE

Up to 10s of power interruption

Full power outage cycle (utility drops out)

slide-44
SLIDE 44

LOAD UTILITY LOAD UTILITY LOAD UTILITY TIME LOAD VOLTAGE

Up to 100ms of paralleled operation

Return to Normal Power (After Outage)

slide-45
SLIDE 45

Closed Transition Risks

  • Why do breakers trip during closed transition transfer?

– Current flow between sources caused by a difference in instantaneous voltage between sources at the instant of closure

  • What causes the difference in voltage?

– Phase angle difference between sources – Difference in RMS voltage between sources – Transient condition on one of the sources

  • Motor stops/starts
  • VFD ramps/down
slide-46
SLIDE 46
  • Closed Transition is not a substitute for a UPS
  • Closed Transition might result in disturbances on transfer

– Frequency and Voltage shift due to less than perfect synchronization – Current spike may result due to voltage difference – Disturbances minimized by Load sequencing

  • Closed transition adds cost due to requirements for protective

relays

  • Closed transition systems can result in project delays due to

additional utility regulations

Closed Transition Considerations

slide-47
SLIDE 47
  • Allows service of ATS without disrupting

power to critical loads.

  • By having two transfer switches

connected in parallel, the bypass transfer switch adds redundancy to the system

  • Applications:

– Critical power and maintenance requirements, including data centers,health care, and waste water treatment facilities

Bypass Isolation Switches

slide-48
SLIDE 48

ATS Bypass

N L E

Bypass Transition Switch

slide-49
SLIDE 49

ATS Bypass

N L E

ATS Bypass

N L E

ATS Bypass

N L E

Connected Test Isolated

  • Normal Operation
  • Bypass open
  • Bypass closed
  • No power across ATS
  • No loss of power to loads

when to Bypass to same source

  • ATS retains sensing and
  • perating functionality
  • Functional testing without

load interruption

  • Bypass carries load
  • ATS removed for service
  • r replacement
  • Manual transfer to

emergency power

Isolation Bypass Positions

slide-50
SLIDE 50
  • Be careful about size and access requirements for bypass

switches

  • A switch in the bypass mode is not automatic

– Remote monitoring of “Switch not in auto”

  • No power interruption required to service ATS

– Non Load break

Bypass Isolation Considerations

slide-51
SLIDE 51
  • Normal ATS with a circuit

breaker on the utility side

– The breaker is a UL listed over- current device

  • Meets NEC requirements for a

Service Entrance equipment

  • Advantages:

– Saves space and cost for a separately mounted circuit breaker

Service Entrance Transfer Switch

slide-52
SLIDE 52

Breaker Pair Transfer Switch

slide-53
SLIDE 53

Breaker Pair Transfer Switch

  • Transfer mechanism is made of two power circuit breakers

– Integral over current protection – Draw out capability (easier to service)

  • Benefits:

– Closed transition with soft loading (option) – Can be also offered as a Service Entrance switch – Facilitates selective coordination - can withstand fault current up to 60 cycles – High level of serviceability

slide-54
SLIDE 54