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Standby Power Systems for Hospitals: The Debate: Is Paralleling Generators a Good Idea?

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Page 1: Standby power systems for hospitals

Standby Power Systems for Hospitals: The Debate: Is Paralleling Generators a Good Idea?

Page 2: Standby power systems for hospitals

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Page 3: Standby power systems for hospitals

Power Control Systems for Mission Critical Facilities

Page 4: Standby power systems for hospitals

Control Systems for Onsite

Power Generation and Distribution

Page 5: Standby power systems for hospitals

Custom Designed and Built

to Your Specific Requirements

Page 6: Standby power systems for hospitals

The Industry’s Most Responsive

Factory-Direct Field Service

Page 7: Standby power systems for hospitals

Standby Power Systems for Hospitals: The Debate: Is Paralleling Generators a Good Idea?

Tom Divine, PE, Project

Manager and Electrical

Engineer, Smith Seckman

Reid, Inc. (SSR), Houston.

Today’s Presenters:

Michael Ivanovich,

Editor-in-Chief & Moderator,

Consulting-Specifying Engineer

Kenneth Lovorn, PE,

President and Chief Engineer,

Lovorn Engineering

Associates, Pittsburgh.

Page 8: Standby power systems for hospitals

Paralleling Generators –

A Good Idea?

May 14, 2009

Tom Divine

Page 9: Standby power systems for hospitals

Answer

Yes, it’s a good idea.

Paralleled systems have:

• more reliability,

• more flexibility, and

• better performance

than single-generator systems

Page 10: Standby power systems for hospitals

Overview

Anatomy of a Generator Paralleling Scheme (simplified)

• Single Generator

• Requirements for Paralleling

• Multiple Generators

• Additional Functions

Costs

Advantages of Paralleled vs. Single Generators

Page 11: Standby power systems for hospitals

Single Generator

Controls required:

• Engine Controller (EC)

– Starts and stops the engine

– Protects engine from damage

– Provides alarms and engine status

• Governor (GOV)

– Controls engine speed

• Voltage Regulator (VR)

– Controls alternator excitation

EC

GOV

VR G

EN

G

BKR

LOAD

ENG – Engine

G - Generator

Page 12: Standby power systems for hospitals

Single Generator - Disadvantages

Engine/generator failure: critical load is at risk

Generator will require scheduled maintenance

• Load is at risk, or

• Temporary unit required

G G

LOAD LOAD

- ON

- OFF

Page 13: Standby power systems for hospitals

Solution – Paralleled Generators

Operate multiple, smaller generators on a common bus

• Maintains service when some, but not all, units fail

• AC generators don’t intrinsically operate in parallel

– Fairly sophisticated controls required for parallel operation

• To initiate

• To maintain

G GG G

Page 14: Standby power systems for hospitals

Requirements for Paralleling

Four requirements for paralleling:

Equal

Frequencies

Equal Phase

Angles

Equal

Voltages

Same Phase

Rotation

Controlled by paralleling system in real time

Go / No Go:

Monitored only

Page 15: Standby power systems for hospitals

Multiple Generators (simplified)

Synchronization sequence:

• All units start

• Master Controller allows first

unit at voltage and frequency

to close

• Other units locked out until

they match in

– phase angle

– voltage, and

– frequency

After synchronization:

• Load Sharing Controller

adjusts setpoints to control

KW and kVAR flows

EC

GOV

VR G

EN

G

BKR

LOAD

MC – Master Controller

LS – Load Sharing Controller

SYNC – Synchronizer

EC

GOV

VR G

EN

G

BKR

LS

MC

SYNC SYNC

Page 16: Standby power systems for hospitals

Reliability

System tolerates loss of a single unit

• With N+1 generators, load is served

when one generator fails

• Ability to selectively shed load

allows system to continue to serve

critical loads if more than one unit

fails

G G

LOAD

Page 17: Standby power systems for hospitals

Additional Functions

Load Shed / Load Restore

• Disconnects loads if overload is imminent

• Responds to loss of generator

• Restores loads as conditions improve

TO LOAD CONTROL

EQUIPMENT – ATS’s,

DISTRIBUTION

G

MC

G

LOAD

Page 18: Standby power systems for hospitals

Additional Functions

Load Demand

• Shuts down unneeded generators

• Generators run more efficiently

– extending available runtime,

– without wet-stacking at low load

• Restarts units as needed

G

MC

G

LOAD

Page 19: Standby power systems for hospitals

Design Considerations

Generator Sizing:

• Minimum size generally driven by performance requirements

– Life Safety and Critical branches on within ten seconds

– Minimum size is the projected peak load on these two branches

• N+1 generators required for reliable service to low-priority loads

– Otherwise, reliability for low-priority loads is actually decreased.

• Provision for load growth must be made at installation

Page 20: Standby power systems for hospitals

Costs

Wide variation in cost of paralleling equipment with:

• Size and number of generators

• Generator voltage

• Required functions

• Level of customization required to meet specifications

• Amount and type of distribution

Range: about $20K - $110K per generator, excluding distribution

• Source: Informal survey of vendors.

Other costs:

• Space requirements

• System complexity requires highly skilled technicians

Page 21: Standby power systems for hospitals

Hardware

Paralleling gear will typically contain:

• A Master Control cabinet

• Multiple Generator Control cabinets

• Distribution cabinets

Alternatives to discrete controls:

• Unitized controllers,

• Distributed controls,

– with control unit and circuit breaker packaged with generator

Page 22: Standby power systems for hospitals

Advantages

Flexibility

• Generator Sizing

– Design to cost or operational targets

– Lower maintenance for smaller units

• Operation

– Wide load range without under-loading units

Page 23: Standby power systems for hospitals

More Advantages

Reliability

• Serves all loads under single-unit failure

• Serves critical loads under multiple-unit failure

Ease of expansion

• Generators can be added as load increases

– If addressed in initial design

Maintenance

• Single generator can be taken out of service in N+1 system

Page 24: Standby power systems for hospitals

And More Advantages

Performance

• Paralleled system is stiffer than multiple single-unit systems

Mature technology

• Large installed base

• Issues are thoroughly tested and well-understood

Page 25: Standby power systems for hospitals

2727

Eaton’s Electrical Group

With 2008 net sales of $15.4 billion, Eaton is recognized

around the world for power quality and innovation

Powerware power quality and reliability products

Cutler-Hammer power distribution and control equipment

Page 26: Standby power systems for hospitals

2828

Cutler-Hammer® Safety

Switch Quick Connect

Cutler-Hammer Roll-Up

Generator Termination BoxCutler-Hammer Switchboard

Quick Connect Systems

Portable Generator Connection Solutions

Page 27: Standby power systems for hospitals

2929

Caterpillar Paralleling

Switchgear*

Cutler-Hammer Automatic

Transfer Switches

*Eaton, through a joint venture relationship with Caterpillar Corporation, offers Caterpillar

Switchgear with PowerLynx Control Technology

Permanent Generator Connection Solutions

Page 28: Standby power systems for hospitals

3030

• MRI, CT, X-ray, PET

• Ultrasound, Mammography

• Trauma Centers

• Cath Labs

• Special and Clinical Labs

• Blood Analyzers

Protecting Diagnostic Imaging: UPS

Power problems cause sensitive electronics to fail resulting

in unplanned downtime, system lock-ups, and expensive

maintenance costs.

UPS for:

Page 29: Standby power systems for hospitals

3131

Protecting IT Systems: UPS

• Pharmacy

• Clinical Labs

• PACS / RIS

• Computerized Physician Order Entry

• Nurses Stations

• Patient Monitoring Systems

• Patient Records

Hospital IT systems are now mission critical. Power

problems cause data loss and equipment failures.

UPS for:

Page 30: Standby power systems for hospitals

3232

Dedicated Consultant Site

www.eaton.com/consultant

• Order free copy of Eaton’s

Consultant Application Guide

• Sign up for Eaton’s

Consultant Newsletter

• Check out our Lunch &

Learn portal

• Product & service information

• And more!

Page 31: Standby power systems for hospitals

Kenneth L. Lovorn, President & Chief Engineer

Lovorn Engineering Associates, LLC

May 14, 2009

Page 32: Standby power systems for hospitals

Hospital Emergency Power

• Dump expensive paralleling equipment

• Design for generator back-up

• Load shedding of Priority 3 equipment

• Concentrate funding on generator sets

Page 33: Standby power systems for hospitals

Advantages

Lower construction costs

Elimination of the paralleling cabinet

Less total area required

Equivalent or better reliability

Design to serve initial load

Ease of expansion as load grows

More difficult to implement

Requires switches in series

Disadvantages

Page 34: Standby power systems for hospitals

Dumping the Paralleling Equipment

Basic paralleling system is sophisticated

Paralleling cabinet fails, system fails

Page 35: Standby power systems for hospitals

Generators and Transfer Switches

Multiple generators without paralleling

Unequal generator sizing

Page 36: Standby power systems for hospitals

Inherit Priority 3 Load Shedding

Additional load transfer switch

Priority 3 loads and transfer switches

Page 37: Standby power systems for hospitals

Real-World ApplicationExisting Hospital 800 kW generator

Expansion of 400 kW emergency capacity

Paralleling system parameters

Add two 800 kW generators

Add a paralleling line-up

Implement a Priority 3 load shedding scheme

Page 38: Standby power systems for hospitals

Real-World Application (con’t)

Multiple generator-transfer switch system Add one 1500 kW generator Add emergency-only distribution panel Priority 1 and 2 loads to 800 kW generator Serve all Priority 3 from 1500 kW generator Second transfer switches for Priority 1 and 2 loads If the 1500 kW generator fails, Priority 3 loads off Savings - $500,000+

Page 39: Standby power systems for hospitals

Real-World Application (con’t)

Electrical Single Lines – Paralleling System

Page 40: Standby power systems for hospitals

Real-World Application (con’t)

Electrical Single Lines – Generator/Transfer Switch System

Page 41: Standby power systems for hospitals

The right way to parallel engine-generators

ASCO Series 7000

Engine-Generator Paralleling

Control Switchgear

Page 42: Standby power systems for hospitals

Custom Engineered

• Hospitals

• Business-critical

facilities

• Commercial

buildings

• Industrial

complexes

Page 43: Standby power systems for hospitals

Digital Control

• Synchronizes, manages and parallels

• Load management, bus optimization

• Sophisticated communications

capabilities

• Power system monitoring

and protection

Page 44: Standby power systems for hospitals

• Design and development

engineering

• Expert product

and project managers

• Knowledgeable

applications engineers

• Skilled sales force

• Best-in-the-industry

commissioning and

field service

Deep Resources

Page 45: Standby power systems for hospitals

Ensure Your Success

Call 800-800-ASCO

Email: [email protected]