Section 1: Introduction
1-1 System.
1-1.1 The MURPHYMATIC
®
Generator Engine Control System,
Series A900 is designed to meet the requirements of the engine
control, shutdown and alarm section of NFPA-110 “Emergency
And Standby Power Systems” specification. The controller also
meets the minimum requirements of NFPA99 “Health Care
Facilities” and the Canadian standard CAN/CSA-C282-M89
“Emergency Electrical Power Supply for Buildings” for engine
control, shutdown and alarm systems. By combining one of the
A900 series controls with generator instruments, a complete engine
generator control panel meeting the above specifications can be
provided.
1-2 Models.
1-2.1 The Series A900 is available in three basic configurations:
1-2.1.1 Model A901 for automatic start and stop generator sets
which includes the minimum shutdowns and alarms per NFPA-
110 Level 1.
1-2.1.2 Model A902 for automatic start and stop generator sets
which includes the minimum shutdowns and alarms per NFPA-
110 Level 2.
1-2.1.3 Model A903 for automatic start and stop generator sets
which includes the minimum shutdowns and alarms per NFPA-
110 Level 2 and seven unlabeled alarm lights for additional
customer specified alarms.
1-2.2 All models are available for 12 or 24 V DC operation.
1-2.3 All models are available for use on either two cycle or four
cycle engines. Models for two cycle engines include an alarm
light for “Air Damper Closed” and an “Overspeed Relay” to
operate the air shutoff solenoid for overspeed shutdown.
1-2.4 Each model is made up of two parts, a Control/Display
module and a Relay module.
1-3 Purpose.
1-3.1 This manual is directed to the installation, maintenance and
operating personnel who will be in day to day contact with the
A900 system. However the basic knowledge gained with this
material will allow those personnel to easily adjust to special
circumstances.
1-4 Definitions.
1-4.1 Throughout this manual, reference is made to organi-
zations, trade names and trademarks which may not be familiar to
the reader. Some of these are:
1-4.1.1 CSA: Canadian Standards Association.
1-4.1.2 CAN/CSA-C282-M89: The standard for Emergency
Electrical Power Supply for Buildings, 1989 Edition.
1-4.1.3 NFPA: National Fire Protection Association.
1-4.1.4 NFPA-70: The National Electrical Code.
1-4.1.5 NFPA-99-1990: The standard for Health Care Facilities,
1990 Edition.
1-4.1.6 NFPA-110-1988: The standard for Emergency And
Standby Power Systems, 1988 Edition.
1-4.1.7 Several terms used in this manual are registered
trademarks of Frank W. Murphy Mfr.
(a) MURPHYMATIC
®
: Refers to all Murphy automatic controls.
(b) SELECTRONIC
®
: A name that is applied to all electronic
controls manufactured by Murphy.
(c) SWICHGAGE
®
: A combination indicating gauge and switch.
(d) TATTLETALE
®
: A term that refers to a shutdown indicating
device or circuit in the control panel.
1-5 How to use this manual.
1-5.1 Section 1, 2, 4, 5, 6 and 7 contain general information that
applies to all A900 models.
1-5.2 Section 3, Model Identification, is broken into seven sub
sections. Section 3-1 allows you to chose the model that best
fits your requirements and Section 3-2 through 3-7 explain each
models features in detail.
Section 2: Specifications
2-1 Enclosure Type.
2-1.1 The A900 Series enclosure is designed to be mounted in a
standard electrical enclosure for indoor use.
2-2 Power Requirements.
2-2.1 The engine controls, shutdown circuits, alarm and shut-
down indicators are powered from the engine starting battery.
The A900 series is available in either 12 or 24 V, negative ground.
2-2.2 The A900 is fused for 3 A maximum current.
2-3 Input Ratings.
2-3.1 All input switches should be dry contact type, maximum
current is 2 mA, 8 V DC or less.
2-3.2 Frequency signal for the speed sensing circuit requires a
minimum input of 2 V rms from a magnetic pickup (preferred) or
from the tachometer terminal of the battery charging alternator.
2-3.2.1 Frequency range of the speed sensing circuits is 25 Hz to
10,000 Hz.
2-4 Output Ratings.
2-4.1 The A900 Control / Display Module has outputs for remote
indication of alarm and shutdowns. These outputs are transistors
that close to the negative supply (sink) and are rated at 1 amp, 30
V DC maximum.
2-4.2 The Control / Display Module also has an output for an
auxiliary starter contactor which is rated 1 A, 30 V DC maximum.
This is a transistor that closes to the positive supply (source).
2-4.3 The Relay Module includes 3 engine control relays with
contact ratings of 7 A, 30 V DC inductive. These powered
contacts must be supplied from an 8 A fuse or circuit breaker
(customer supplied). The 3 alarm relays have dry contacts, also
rated at 7 A, 30 V DC maximum.
2-5 Field Wiring Connections.
2-5.1 All field wiring connections are barrier terminal blocks, UL
rated for 15 A, 300 V.
2-6 Operating Temperature.
2-6.1 The operating temperature range of the A900 is -4°F to
158°F (-20°C to 70°C.)
Section 3: Model Identification
3-1 Model Numbers.
3-1.1 A901-12 and A901-24: These models are designed for an
automatic start four cycle engine driven generator, and
include the shutdown and alarm points recommended in NFPA-
110-1988 “Emergency and Standby Generator Systems” for Level
1 installations. These controllers also meet or exceed the
minimum requirements of NFPA99-1990 “Health Care Facilities”
and with the addition of a Low Water Level alarm, the Canadian
standard CAN/CSA-C282-M89 “Emergency Electrical Power
Supply for Buildings”. The suffix numbers -12 and -24 indicate
the engine starting battery voltage.
3-1.2 A901-2-12 and A901-2-24: These models are designed for
1