NFPA110 OverviewThis material is based on NFPA110-2010

Portions of this material are reprinted with permission from NFPA 110 Standard for Emergency and Standby Power Systems®, Copyright © 2010, National Fire Protection Association, Quincy, MA 02169. This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety.

NFPA110 Overview

Purpose

� NFPA 110 describes minimum requirements for EPSS system performance that is necessary for life safety applications.– A unique requirement, not addressed in most other standards

– EPSS (emergency power supply system) is an electro-mechanical system• Standards tend to be either electrical or mechanical

– EPS (emergency power supply) is the source of power in EPSS

� Intent of standard is to achieve maximum system reliability

� Why is this needed?– Example: Alternator voltage dip on load application

NFPA110 Overview

What’s the voltage dip?

� 18%, right?

� Nope! This is alternator only!

VOLTAGE ROLLOFF

0

20

40

60

80

100

120

45 50 55 60 65

FREQUENCY%

VO

LTA

GE

NFPA110 Overview

Terminology

� EPSS: Emergency Power Supply Systems

� EPS: Emergency Power Supply

� Level:– 1: critical to life safety– 2:

� Class: – duration of system

operation� Type:

– time period that the load can be without power

NFPA110 Overview

The Critical Paragraph

� 2700kW, 1800RPM

� Across the line bolted fault response

NFPA110 Overview

Prototype Test Requirements

� Bad news: There’s no common agreement on detailed requirements for prototype test

� Some of the requirements are hardware related� Some of the requirements are installation related� Some requirements depend on proper settings and operation� Best available control is required (especially AVR, governor)� Manufacturer of genset to certify compliance

NFPA110 Overview

Prototype, Production, and Site Testing� Prototype tests validate the design

– May be destructive

– Short circuit, life, performance, drop tests, out of phase paralleling, seismic, overload, starting time, etc.

� Production tests validate proper assembly– Requires good production control (ie, ISO9000)

– Starting, transient performance (gain tuning), full load capability (0.8 pf), block load capability

� Site commissioning tests validate the installation– Starting, ability to carry full load, accessory installation, black

start test, block load test

� Regular exercise and tests verifies proper maintenance

NFPA110 Overview

Site Test: Cold Start Requirement

� Requires coolant heaters to be continuously operating

� Typical requirement is that genset must be in a 40F environment in order to start in 10 seconds, and pick up full load

� Alarm when engine temperature too low to start and pick up load in 10 seconds

NFPA110 Overview

Site Test: Full Load Operation

� Generator set must be able to carry required loads for duration of time based on defined Class

� Evaluate based on site conditions

� Impact of installation problems…

NFPA110 Overview

Importance of Starting System

� Properly sized batteries

� Proper starting cycle– Diesels can be

continuous crank

� Proper charger– features

– recharge time

NFPA110 Overview

Critical Charger Performance

� Sufficient capacity to recharge batteries within 24 hours (Level 1)– 225 amp-hour battery recharges in 22.5 hours with 10A

charger• Charger designed to charge a fully discharged battery

• Need TWO 10A chargers for most 24V diesels

� Critical to get charger that properly “floats” when battery is fully charged

� Proper charge rate depends on temperature compensation—especially for outdoor gensets

NFPA110 Overview

� Emissions-controlled engines include these functions by default, plus many more

� Operator panels are cheap

� Specify display all engine and alternator data for all applications

� Remote annunciation required

NFPA110 Overview

Engine Cooling Systems

� How often do you do commissioning at full load on the hottest day of the year?

Air Flow In

90F 110F 125F

NFPA110 Overview

Alternator Requirements

� What the heck is “amortisseur”?

� Protects alternator field during short circuit conditions

� Common on larger machines, not so much on smaller

Amortisseur Windings

NFPA110 Overview

Other Alternator Requirements

� Stable with all loads (maybe hard)– Much of a modern facility load is non-

linear

– Low cost voltage regulators may have operational problems

� Operate at the correct voltage at all loads (easy)

� Sized to prevent load drop out due to voltage dip– Remember

engine/alternator volts/hz function

NFPA110 Overview

Transfer Switch Requirements� Not very hard to meet…� It’s got to work (duh!)� Separate enclosure for each ATS� Must have commonly available time delays

– Start, stop, transfer, retransfer– Controlled operation speed for motor loads (my opinion)

� Source availability sensing– All-Phase undervoltage sensing line side– Single phase undervoltage and frequency sensing on genset side

� Mechanical & electrical interlock, except closed transition (???)� Exercisor clock in system, test switch, position indication, switched

neutral pole when required� Labeled as LISTED for use in emergency circuits� Suitable for fault currents…

NFPA110 Overview

Selective Coordination

� UL short time ratings required for success in multiple level systems with ATS upstream

NFPA110 Overview

Selective Coordination (Bonus Info)

� Move breakers off generator set to remote switchboard or breaker boxes for each load type

– Make selective coordination task the responsibility of one party– Includes Service Entrance requirements for outdoor generators

� Overload (ANSI 51 Function) is required but is not necessarily required to be located on the generator

– A main breaker in the switchboard may provide this function– See NEC Handbook

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NFPA110 Overview

Other Installation Points

� Dedicated genset room– Separated from normal

service

� Minimize risk of flood

� Accessible

� Battery lighting, lighting from ATS

� Doesn’t vibrate the building

NFPA110 Overview

Other Installation Points (con’t)

� Cooling system properly designed, including provisions for service

� Probably need alternator heaters for outdoor gensets

� Ventilation system allows enough airflow

� Don’t do something stupid with the exhaust system

NFPA110 Overview

Fuel System

� Perhaps your biggest risk…– Easiest to do wrong

– 2nd most likely reason for unplanned shutdown

� Design depends on somewhat on engine manufacturer

� More sensitive with emission-controlled engines

� Many codes and standards to comply with– Subject to local interpretation

� Your generator guy is your friend…

NFPA110 Overview

Outdoor Generator Sets (NEW)

� Coolant heaters are not sufficient to meet this requirement

� Guideline: enclosures maintained at a minimum temperature of 40ºF, assuming coolant heaters designed as in past (now required)

NFPA110 Overview

Installation Acceptance Testing� Detailed requirements are in the standard

– Rewritten in 2010 version– Specify: “System shall be tested as required in

NFPA 110-2010 section 7.13.4.1.”� Cold start test

– Engine(s) in normal mode, with heaters running– Must start and pick up all emergency loads

� 2-Hour full load test– 0.8 pf, unless tested at factory at 0.8 pf– Parallel gensets can be used for this

� Full load step test– 0.8 pf gives different results than 1.0 pf

� Paralleled gensets can be load tested individually� Standard requires testing the engine safeties and cycle

crank– A bit of a waste, as all engines are emissionized, and have

fail safe sensor circuits; factory test is allowed with report� Documentation Required

– Prototype test certification including torsionals, test certificate

– Installation certification

NFPA110 Overview

� A set of manuals and other operating information as well as recommended spares are required to be located in the generator room for level 1 systems (recommended for all)

� A routine maintenance and test program must be implemented for all systems– Monthly tests under load

• At least 30% of rated load or load sufficient to develop minimum exhaust temperature recommended by engine maker– Some exceptions are available for diesel gensets

• ATS must be operated every month, so using the ATS to “test with load” is a good idea

� Annual inspection, cleaning and operational testing of ATS and breakers is required

� A test of the entire EPSS for Level 1 systems, including all assigned loads is required every 36 months– Duration of test is based on class, maximum 4 hours

– May be combined with annual test

– Requires minimum of 75% of rated load

� Permanent record of test/exercise schedule, test results, and maintenance/service on the system is required– Samples are in the standard

sample

Ongoing Maintenance and Testing

NFPA110 Overview

NFPA 110

� Requirements to achieve maximum on-site power system reliability

� System Focus

� Practical, but not cheap

� See appendix for some practical advice on power system design and operation

NFPA110 Overviewreturn