Alpha Technologies GMX-915 User manual

Technical Manual
GMX-915 Models
Effective: March, 2006
GMX
Standby Power Supply
Alpha Technologies

Power
Alpha Technologies
®

Contacting Alpha Technologies: www.alpha.com
or
For general product information and customer service (7 AM to 5 PM, Pacific Time), call
1-800-863-3930
For complete technical support, call
1-800-863-3364
7 AM to 5 PM, Pacific Time, or 24/7 emergency support
GMX Standby Power Supply
017-932-B0-001, Rev A
Effective Date: March, 2006
Copyright© 2006
Alpha Technologies, Inc.
Notice of FCC Compliance
Per FCC 47 CFR 15.21:
Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the
equipment.
Per FCC 47 CFR 15.105:
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the
instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to
cause harmful interference in which case the user will be required to correct the interference at their own expense.
3
member of The Group
TM
Alpha shall not be held liable for any damage or injury involving its enclosures, power supplies, generators,
batteries, or other hardware if used or operated in any manner or subject to any condition not consistent with
its intended purpose, or is installed or operated in an unapproved manner, or improperly maintained.
Photographs contained in this manual are for illustrative purposes only. These photographs may not match
your installation.
NOTE:
Operator is cautioned to review the drawings and illustrations contained in this manual before proceeding. If
there are questions regarding the safe operation of this powering system, please contact Alpha Technologies
or your nearest Alpha representative.
NOTE:
NOTE:

4017-932-B0-001, Rev. A
Table of Contents
Safety Notes.......................................................................................................................... 7
1.0 Introduction to the GMX Power Supply..................................................................... 13
1.1 Terminal Block Overview................................................................................ 14
1.2 Inverter Overview........................................................................................... 15
1.3 Optional Status Monitoring Modules.............................................................. 16
1.4 Optional Features .......................................................................................... 17
2.0 Theory of Operation.................................................................................................. 18
2.1 AC (Line) Operation....................................................................................... 18
2.2 Standby Operation......................................................................................... 18
2.3 Charger Operation ......................................................................................... 19
3.0 Installation................................................................................................................. 21
3.1 Installation Procedure .................................................................................... 22
3.2 Installing the Optional AC Indicator Lamp...................................................... 23
3.3 Service Power Inserter (SPI) ......................................................................... 25
4.0 Configuration ............................................................................................................ 27
4.1 Micro Board Setup ......................................................................................... 27
4.2 AC Output Voltage Reconfiguration............................................................... 28
5.0 Operation.................................................................................................................. 29
5.1 Start-up and Test............................................................................................ 29
5.2 Smart Display................................................................................................. 32
5.2.1 Operation Normal................................................................................ 34
5.2.2 Additional Information Display............................................................. 35
5.2.3 Setup Menu......................................................................................... 36
5.2.4 Alarm Indications................................................................................. 39
5.2.5 Control Panel LEDs............................................................................. 41
5.2.6 Detailed Menu Structure and Navigation ............................................ 42
5.3 Smart Display Glossary ................................................................................. 44
5.4 Automatic Performance Test.......................................................................... 46
5.5 Providing Power via External Source............................................................. 47
5.5.1 DC Powering....................................................................................... 47
5.5.2 AC Powering ....................................................................................... 47
5.5.3 Using a Truck-mounted Inverter or Generator .................................... 48
5.6 Resumption of Utility Power........................................................................... 49

5
017-932-B0-001, Rev. A
Table of Contents, continued
6.0 GMX Power Supply Maintenance............................................................................. 50
6.1 Check Battery Open Circuit Voltage .............................................................. 50
6.2 System Information........................................................................................ 50
6.3 Check Battery Voltage Under Load................................................................ 51
6.4 Check Battery Charger Voltage ..................................................................... 52
6.5 Check Battery Terminals and Connecting Wires............................................ 52
6.6 Check Output Voltage.................................................................................... 52
6.7 Check Output Current.................................................................................... 52
6.8 Replacing the Metal Oxide Varistors.............................................................. 53
6.9 Maintenance Log ........................................................................................... 54
7.0 Specifications............................................................................................................ 55
7.1 Safety and EMC Compliance......................................................................... 56
8.0 Troubleshooting ........................................................................................................ 57
8.1 Return/Repair Information.............................................................................. 57
8.2 Parts Ordering Instructions ............................................................................ 57
8.3 Emergency Shutdown.................................................................................... 58

6017-932-B0-001, Rev. A
List of Figures and Tables
Fig. 1-1, GMX Power Supply............................................................................................... 13
Fig. 1-2, GMX Terminal Block Overview.............................................................................. 14
Fig. 1-3, Inverter Overview .................................................................................................. 15
Fig. 2-1, Charger Modes...................................................................................................... 19
Fig. 2-2, GMX Block Diagram.............................................................................................. 20
Fig. 3-1, AC Indicator........................................................................................................... 23
Fig. 3-2, Wire/Connector Assembly..................................................................................... 23
Fig. 3-3, ACI Connection ..................................................................................................... 24
Fig. 3-4, SPI Cover Removal............................................................................................... 25
Fig. 3-5, Coaxial Cable Insertion and Securing................................................................... 25
Fig. 3-6, Cover Replaced, SPI Switched On ....................................................................... 26
Fig. 3-7, SPI Grounding Lug................................................................................................ 26
Fig. 3-8, Enclosure Ground Bar........................................................................................... 26
Fig. 4-1, Micro Board Settings............................................................................................. 27
Fig. 4-2, Transformer Output Tap Connector....................................................................... 28
Fig. 5-1, Configuration Screen............................................................................................. 29
Fig. 5-2, Smart Display........................................................................................................ 33
Fig. 5-3, Normal Operation Display ..................................................................................... 34
Fig. 5-4, Additional Info Display........................................................................................... 35
Fig. 5-5, Setup Menu Display .............................................................................................. 38
Fig. 5-6, Smart Display LEDs .............................................................................................. 41
Fig. 6-1, MOV Removal....................................................................................................... 53
Fig. 6-2, MOV Replacement................................................................................................ 53
Fig. 8-1, Emergency Shutdown ........................................................................................... 58
Table 5-1, Setup Menu Parameters..................................................................................... 39
Table 5-2, Major Alarms....................................................................................................... 40
Table 5-3, Minor Alarms....................................................................................................... 40

7
017-932-B0-001, Rev. A
Safety Notes
Review the drawings and illustrations contained in this manual before proceeding. If there are any questions
regarding the safe installation or operation of this product, contact Alpha Technologies or the nearest Alpha
representative. Save this document for future reference.
To reduce the risk of injury or death, and to ensure the continued safe operation of this product, the following
symbols have been placed throughout this manual. Where these symbols appear, use extra care and
attention.
Safety Precautions
• Only qualified personnel may service the GMX Power Supply.
• Verify the voltage requirements of the equipment to be protected (load), the AC input voltage to the power
supply (line), and the output voltage of the system prior to installation.
• Equip the utility service panel with a properly rated circuit breaker for use with this power supply.
• When connecting the load, DO NOT exceed the output rating of the power supply.
• Always use proper lifting techniques whenever handling the power supply or batteries.
• The GMX Power Supply contains more than one live circuit! Even though AC voltage is not present at the
input, voltage may still be present at the output.
• If batteries are being stored prior to installation, charge at least once every three months to ensure
optimum performance and maximum battery service life.
• To reduce the chance of spark, and wear on the connectors, always switch the inverter’s battery circuit
breaker off before connecting or disconnecting the battery pack.
• The battery pack, which provides backup power, contains dangerous voltages. Only qualified personnel
should inspect or replace batteries.
• In the event of a short circuit, batteries present a risk of electrical shock and burns from high current.
Observe proper safety precautions.
• Always wear protective clothing, insulated gloves and eye protection (safety glasses or face shield)
whenever working with batteries.
• Always carry a supply of water, such as a water jug, to wash the eyes or skin in the event of exposure to
battery electrolyte.
The use of ATTENTION indicates specific regulatory/code requirements that may affect the placement of
equipment and /or installation procedures.
ATTENTION:
A NOTE provide additional information to help complete a specific task or procedure.
NOTE:
The use of CAUTION indicates safety information intended to PREVENT DAMAGE to material or
equipment.
CAUTION!
WARNING presents safety information to PREVENT INJURY OR DEATH to the technician
or user.
WARNING!

8017-932-B0-001, Rev. A
Safety Precautions, continued
• Do not allow live battery wires to contact the enclosure chassis. Shorting battery wires can result in a fire
or possible explosion.
• Always replace batteries with those of an identical type and rating. Never install old or untested batteries.
• Avoid using uninsulated tools or other conductive materials when handling batteries or working inside the
enclosure.
• Remove all rings, watches and other jewelry before servicing batteries.
• Spent or damaged batteries are environmentally unsafe. Always recycle used batteries. Refer to local
codes for proper disposal of batteries
Battery Safety Notes
• Always refer to the battery manufacturer’s recommendation for selecting correct “FLOAT” and “ACCEPT”
charge voltages. Failure to do so can damage the batteries.
• Verify the GMX battery charger's “FLOAT” and “ACCEPT” voltage settings. See Section 5.2.3, Setup
Menu.
• Batteries are temperature sensitive. During extremely cold conditions, a battery’s charge acceptance
is reduced and requires a higher charge voltage. During extremely hot conditions, a battery’s charge
acceptance is increased and requires a lower charge voltage. To compensate for changes in temperature,
the battery charger is temperature compensating.
• If the batteries appear to be overcharged or undercharged, first check for defective batteries and then
verify the correct charger voltage settings.
• To ensure optimum performance, inspect batteries every three to six months for signs of cracking,
leaking, or unusual swelling (note that some swelling is normal).
• Check battery terminals and connecting wires. Clean battery terminal connectors periodically and
retighten to approximately 50 inch-pounds. Spray the terminals with an approved battery terminal coating
such as NCP-2.
• Check battery voltages UNDER LOAD. Use a load tester if available. Differences between any battery in
the set should not be greater than 0.3VDC.
• Refer to the battery manufacturer’s recommendation for correct charger voltages.
• Number the batteries (1, 2, 3, etc.) inside the enclosure for easy identification (refer to the appropriate
enclosure installation guide).
• Establish and maintain a battery maintenance log (see Section 6.9).
If installed, disconnect the AlphaGuard (AG-CMT) prior to measuring battery voltage.
NOTE:
Even with a AG-CMT present in the system, any battery which fails the 0.3V load test must be replaced with
an identical type of battery.
NOTE:
Always verify proper polarity of cables before connecting the batteries to the power module. The batteries are
clearly marked for polarity. If the cables become interchanged at the batteries the battery breaker will trip.
NOTE:

9
017-932-B0-001, Rev. A
Utility Power Connection Notes
Connecting to the utility should be performed only by qualified service personnel and in compliance with local
electrical codes. Connection to utility power must be approved by the local utility before installing the power
supply.
ATTENTION:
UL and NEC require that a service disconnect switch (UL listed) be provided by the installer and be connected
between the power source and the GMX Power Supply. Connection to the power supply must include an
appropriate service entrance weather head.
ATTENTION:
In order to accommodate the high-inrush currents normally associated with the start-up of ferroresonant
transformers (400A, no-trip, first-half cycle), either a “high-magnetic” or HACR (Heating, Air Conditioning,
Refrigeration) trip breaker must be used. Do not replace these breakers with a conventional service entrance
breaker. Alpha recommends ONLY Square D breakers because of increased reliability in this powering
application. High-magnetic Square D circuit breakers and BBX option (UL Listed service entrance) are
available from Alpha Technologies.
NOTE:
GMX Line Cord Options Alpha P/N
Line Cord, 3-conductor, 12AWG, NEMA 6-20P (US) 875-254-11
Line Cord, IEC 320 to NEMA 5/20P, SJT 12AWG (US) 875-254-10
Line Cord,3C, #14, SCHUKO/320 C19 RECT, 1M (EU) 875-432-10
Line Cord, 3C, #14, SCHUKO/IEC 320 C19 REPT, 2.5M (EU) 875-433-10
Line Cord,3C, #14, BS546/IEC 320 C19 RCPT, 1M (India) 875-434-10
Line Cord,3C, #14, BS1363/IEC 320 C19 RCPT, 2M (UK) 875-435-10
Line Cord,3C, CHN/IEC 320 C19 RCPT, 1M (China) 875-436-10
Line Cord, 3-conductor, 12AWG, NEMA 6-15P (US) 875-471-10
Description Alpha P/N Square D Part Number
240V Installation — HACR (15A) 470-224-10 QO215
120V Installation — High-magnetic (20A) 470-017-10 QO120HM
120V Installation — High-magnetic (15A) 470-013-10 QO115HM
BBX — External Service Disconnect 020-085-10 QO2-4L70RB
BBX — External Service Disconnect 020-141-10 QO8-16L100RB

10 017-932-B0-001, Rev. A
Utility Power Connection Notes
In most cases, the following configurations qualify for service entrance use when wiring a duplex receptacle
to a service disconnect. Other codes may also apply. Always contact your local utility to verify that the wiring
conforms to applicable codes.
120VAC 20A Service, GMX 115V, U.S. Domestic Models
These configurations are equipped with a 120VAC duplex receptacle which provides power to the power
supply and peripheral equipment. The receptacle, NEMA 5-20R, is protected by a single-pole, 20A High
Magnetic (HM) circuit breaker located inside the service entrance. Wiring is typical 12AWG per NEC code,
and a grounding clamp, located on the enclosure, facilitates dedicated grounding.
To bond the box to a neutral plate, use the long green bonding screw provided (Alpha P/N 523-011-10).
Typical 120 VAC 15A Receptacle Wiring, 5-15R Typical 120 VAC 20A Receptacle Wiring, 5-20R
(P/N 531-006-10)
(P/N 531-003-10)
Neutral
(White) Ground
(Green)
LI
(Black)
Neutral
(White)
LI
(Black)
Ground
(Green)
ATTENTION:
NOTE:
L1 Black
Typical 120VAC Service Entrance Wiring
To Utility
Neutral (White)
Neutral Bus
To Enclosure Receptacle
L1 Black
Grounding Point
(made to enclosure wall)
Copper Ground Wire
#8AWG (minimum)
Breaker

11
017-932-B0-001, Rev. A
240VAC Service Entrance, GMX 225V, U.S. Domestic Models
These configurations are equipped with a 240VAC duplex receptacle to provide power to the power supply
and peripheral equipment. The receptacle, NEMA 6-15R, is protected by a single, 2-pole, common trip 15A
circuit breaker located inside the service entrance. Wiring is typical 14AWG per NEC code, and a grounding
clamp, located on the enclosure, facilitates dedicated grounding.
Utility Power Connection Notes, continued
Typical 220, 230, 240VAC 15A Service Entrance Wiring, International
To bond the box to a neutral plate, use the long green bonding screw provided (Alpha P/N 523-011-10).
NOTE:
Line (Black)
Neutral Bus
LI
Grounding Point Made
to Enclosure Wall
Copper Ground Wire
#8 AWG (Minimum)
Breaker
To Utility
Neutral (White)
220, 230, 240VAC Service Entrance, GMX 225V, International Models
Typical 240VAC Service Entrance Wiring, U.S. Domestic Markets
Line (Black)
Neutral Bus
LI
Grounding Point Made
to Enclosure Wall
Copper Ground Wire
#8 AWG (Minimum)
Breaker
To Utility
Neutral (White)
L2
L2 L1

12 017-932-B0-001, Rev. A
Grounding Connection Notes
In order to provide a ready, reliable, source of backup power, it is necessary to establish a grounding system
that provides for the safety of service personnel and for the proper operation and protection of equipment
within the network.
Safety Ground
The safety ground is a two-part system. The first part is a return path for stray current back to the input
breaker, and the second is a return path from the Alpha enclosure to a second ground rod.
Typically, the utility ground provides a return path to the input breaker or fuse panel by means of a connection
to an appropriate driven ground rod at the base of the power pole. This path must meet National Electric Code
(NEC) standards and local codes to ensure the breaker will open and prevent unwanted current flow from
posing a hazard to service personnel.
The second part of the safety ground arrangement is the ground path between the Alpha enclosure and a
second ground rod located at least six feet away from the driven ground rod at the power pole. The second
ground rod and enclosure are connected via #6AWG solid copper wire buried at a depth of 8 to 12 inches. The
wire is connected to a ground lug on the back of the cabinet (for pole-mounted enclosures), or to a ground
lug inside the cabinet (for ground-mounted enclosures). Connection to the ground rod is made with a listed
grounding clamp suitable for direct burial, or by exothermic weld. Normally it is specified that the impedance of
this ground can be no greater than 25 ohms at 60Hz. However, if dual ground rods are installed approximately
eight feet apart, it is not necessary to measure the impedance of the ground rods (it is assumed that the
impedance specification is met).
Signal Ground
For proper operation, the Service Power Inserter (SPI) must be securely grounded to the enclosure chassis.
For systems utilizing ESM/DSM status monitoring, the ground connection is made through a separate chassis
ground block (Alpha P/N 162-028-10).
Strike (Lightning) Ground
Lightning strikes, grid switching, or other aberrations on the power line all have the potential to cause “fast
rise-time currents” that can cause damage to the powering system. Without a low-impedance path to ground,
the current, while traveling through wires of varying impedance, can produce high voltages that will damage
the powering equipment. The most viable method available to protect the system from damage is to divert
these unwanted fast rise-time currents along a low-impedance path to ground. A low-impedance path to
ground will prevent these currents from reaching high voltage levels and posing a threat to equipment. The
single-point grounding system provides a low-impedance path to ground, and the key to its success is the
proper bonding of the ground rods, so the components of the grounding system appear as a single point of
uniform impedance.
Low impedance grounding is mandatory for personnel safety and critical for the proper
operation of the cable system.
WARNING!

13
017-932-B0-001, Rev. A
1.0 Introduction to the GMX Power Supply
The Alpha family of GMX Uninterruptible Power Supplies is designed for powering signal processing
equipment in cable television and broadband LAN distribution systems. The GMX provides a critical
load with current-limited, regulated, AC power that is free of spikes, surges, sags and noise.
During AC line operation, AC power entering the power supply is converted into a quasi square wave
and is regulated by a ferroresonant transformer at the required output voltage. The regulated voltage
is connected to the load via the VOUT ± terminal block connections, and some power is directed to the
battery charger to maintain a float charge on the batteries.
When the incoming AC line voltage significantly deviates from normal, the GMX Power Supply
automatically switches from the AC line to Standby mode, maintaining power to the load. During the
switch to standby operation, energy in the module’s ferroresonant transformer continues to supply
power to the load. While in Standby mode, the GMX powers the load until the battery voltage reaches
a low-battery cutoff point.
When utility power returns, the GMX Power Supply waits a short time (approximately 10 to 20
seconds) for the utility voltage and frequency to stabilize, and then initiates a smooth, in-phase
transfer back to AC line power. Once the transfer is complete, the battery charger recharges the
batteries in preparation for the next event.
Key components of the GMX Power Supply include a line-conditioning ferroresonant transformer,
resonant capacitor, transfer isolation relay, and inverter. The inverter contains circuitry for the three-
stage temperature-compensated battery charger, DC to AC converter (inverter), AC line detector, and
Smart Display. An optional communciation module provides remote status monitoring.
The GMX Power Supply features:
• Line Interactive Ferro Technology (LIFT)
• Smart Display
• Built-in programmable battery self-test
• 3-stage temperature compensated battery charger
• Automatic battery detection
• Field programmable flash memory
• Digital status monitoring (optional)
Fig. 1-1, GMX Power Supply

14 017-932-B0-001, Rev. A
1.0 Introduction to the GMX Power Supply, continued
1.1 Terminal Block Overview
The GMX terminal block is located on the front left-hand side of the power supply. Below is a
brief description of each terminal.
Connections:
• LRI (Local/Remote Indicator): The LRI lamp option is used in conjunction with the
Automatic Performance Feature and connects to the LRI ± terminals on the terminal
block. The LRI circuit is rated at 12VDC, 250mA. This option duplicates the function
of the red ALARM LED by illuminating an externally mounted red lamp for standby
operation.
• VOUT ± (Voltage Out): The AC output terminal is clearly marked for easy identification.
The Service Power Inserter (SPI) connects into the VOUT ± terminals.
• GND (Ground): A ground wire (12-14AWG recommended) can be connected to this
terminal to permanently tie the chassis to utility ground. This may be desired when an AC
generator is connected to the power supply, because the chassis ground through the line
cord is removed when the line cord is plugged into the generator.
• V SEL (Voltage Select): The voltage select jumper can be configured for either the 63V
output (shown position), or the 87V output.
Fig. 1-2, GMX Terminal Block Overview
NOTE:
If using the Alpha SPI with the GMX power supply, cut the Anderson connector off of the SPI and strip the
wires 3/8".

15
017-932-B0-001, Rev. A
1.0 Introduction to the GMX Power Supply, continued
1.2 Inverter Overview
The inverter provides uninterrupted power to the ferroresonant transformer (via the batteries)
during line failures. During line operation, the inverter charges the batteries using a three-
stage (Bulk, Accept, and Float) charger.
Components:
• Smart Display: All operational functions, system testing, setup items, and alarms are
available via the Smart Display panel on the front of the GMX Power Supply (the Smart
Display is covered in detail in Section 5.2). Display functions are accessible by pressing
any of the four keys: ESCAPE, UP, DOWN, and ENTER. Backlighting is activated when
any of the four keys are pressed, and stays illuminated for one hour. There are four
levels of menu items: Normal operation, Additional Information, Setup, and Alarms. Press
ENTER to display one level lower. Press ESCAPE to display one level higher. Press
ESCAPE to toggle between the main menu and alarm menu when alarms are present.
• Battery Breaker: The battery breaker disconnects the batteries from the inverter's
DC circuit. With the battery breaker turned off, the GMX Power Supply will not transfer
to standby mode, the inverter is disabled, and the battery charger cannot charge the
batteries. If an overcurrent is detected in the DC circuitry the breaker will trip.
• Battery Input Connector (Red = Positive; Black = Negative): The batteries plug directly
into the inverter’s battery connector. The connector is color-coded and fits in one direction
only.
• Inverter Cooling Fan: The inverter is equipped with a cooling fan that operates during
standby operation, or when the inverter heatsink temperature reaches 85°C. The fan
stays on until the temperature drops below 75°C. The fan also operates any time a self-
test is in progress.
• Battery Temp Probe Connector: The Remote Temperature Sensor (RTS) plugs directly
into the temperature probe (RJ-11C type) connector. The sensor end of the RTS is routed
to the battery compartment and taped directly to the side of the center battery (See Fig.
1-8). The RTS provides battery temperature measurements used to adjust the battery
charge voltage.
Fig. 1-3, Inverter Overview
Status LEDs Smart Display Battery Input
Battery
Breaker
Battery Temperature
Probe Connector
Inverter
Cooling Fan

16 017-932-B0-001, Rev. A
1.0 Introduction to the GMX Power Supply, continued
1.3 Optional Status Monitoring Modules
The GMX Power Supply supports a number of Alpha Technologies communications modules.
The modules may be ordered factory-installed or as user-installed field upgrades.
Handle these modules with extreme care. Circuit boards and logic upgrades are static-sensitive and
susceptible to damage.
CAUTION!
AlphaGuard™ Battery Charge Management System
The AlphaGuard Battery Charge Management System
extends battery life by providing the precise voltage required
for each battery. You can replace single batteries as they
fail, not the entire string. It spreads charge voltage equally
across batteries, and batteries no longer need to be matched.
It adjusts for battery changes as they age. The optional
communications module monitors individual battery voltage
during inverter operation, protecting against damage from over
discharge. The AG-CMT-3 model supports 36V battery strings.
The AG-CMT-4 supports 48V battery strings. Refer to the
AlphaGuard Installation Instructions, Alpha P/N 012-306-C0,
for detailed information.
AlphaNet ESM
AlphaNet™Ethernet Status Monitor (ESM)
The AlphaNet ESM (Alpha P/N 745-814-20) allows monitoring
of your GMX Power Supply via a network connection. Advanced
features and networking services provide for quick reporting and
access to critical powering information, keeping your broadband
network running reliably.
The AlphaNet ESM supports the standard networking protocols
required for effective power network management. The ESM
provides efficient network status monitoring and diagnostics using
Simple Network Management Protocol (SNMP) and standard
MIBs. A Web interface enables authorized personnel direct
access to powerful, advanced diagnostics using a common Web
browser. No custom software is required. Refer to the AlphaNet
ESM/DSM Installation and Operation Manual, Alpha P/N 704-
782-B0, for more information.
AlphaNet™DOCSIS Status Monitor (DSM)
The AlphaNet DSM (Alpha P/N 745-825-10) provides the
same funtionality as the AlphaNet ESM, but features an
environmentally hardened embedded DOCSIS®cable modem
for convenience and reliability.
AlphaNet DSM
AlphaGuard CMT

17
017-932-B0-001, Rev. A
1.0 Introduction to the GMX Power Supply, continued
1.4 Optional Features
The following options can be factory installed, or upgraded in the field by the user:
Local and Remote Indicator (LRI)
The LRI (red) lamp is located on the outside of pole-mount enclosures. During normal AC
line operation, the LRI remains off. The LRI comes on only when the power supply is running
in Standby Mode. Whenever a fault is detected during self-test, the LRI flashes to indicate
that service is required. The LRI is a simple form of status monitoring that allows operators to
check the operational status of the power supply without having to climb the pole and open
the enclosure.
AC Indicator (ACI)
The AC Indicator (green lamp) is located next to the LRI on the outside of pole-mount
enclosures. As long as there is voltage present at the output, the ACI remains on. As with the
LRI, it acts as a simple form of status monitoring that allows cable technicians to check the
output status of the power supply without having to climb the pole and open the enclosure.
Alpha recommends using the ACI-LL (long life LED) because it provides much longer life
than the original light bulb design. Models for 60V and 90V are available. ACIs are not
recommended for ground mount enclosures.
LA-P+ 120V, 240V (Lightning Arrestor)
The LA-P+ plugs directly into the enclosure’s convenience outlet, to provide additional
protection from voltage spikes caused by lightning and other power disturbances. It
eliminates the need for hard-wired MOVs. No additional wiring is necessary.
APP90S /APP9022S (Service Power Supply)
The APP90S/APP9022S is a portable, non-standby power supply that provides conditioned
AC power to the load when the main power module is out of service. An internal tap allows
the APP90S/APP9022S to be set for 90/75/60VAC applications. Using a 15A or 25A SPI
(Service Power Inserter), power can be transferred from the APP9015S/APP9022S to the
load.
Utility safety ground must meet NEC standards.
ATTENTION:

18 017-932-B0-001, Rev. A
2.2 Standby Operation
When incoming AC line voltage drops or rises significantly, or a complete power outage
occurs, the GMX line monitor activates standby operation. During the transfer from AC line to
standby operation, the battery powered inverter comes on-line as the isolation relay opens to
prevent AC power from back-feeding to the utility. The energy contained in the ferroresonant
transformer continues to supply power to the load. The following changes also occur within
the GMX Power Supply:
• The isolation relay opens to disconnect the AC line from the primary winding of
ferroresonant transformer.
• The control logic drives the inverter field-effect transistors (FETs) on and off. This
switching action converts the DC battery current into AC current in the inverter windings
of the ferroresonant transformer, which provides regulated power to the load.
• The control logic, which includes a microprocessor and other circuits to protect the
inverter FETs from overcurrent damage, monitors the condition of the batteries and the
inverter during standby operation. Since a prolonged AC line outage would severely
discharge the batteries, resulting in permanent damage, the control logic disables the
inverter when the batteries drop to approximately 10.5VDC per battery (31.5VDC in a
three-battery set, or 42VDC in a four-battery set).
When acceptable AC line voltage returns, the power supply transfers back to AC line
operation within 10 to 20 seconds. This delay allows the AC line voltage and frequency to
stabilize before the control logic phase-locks the inverter’s output to the utility input. The
control logic then de-energizes the isolation relay, reconnects the AC line to the primary of
the ferroresonant transformer and disables (turns off) the inverter. This results in a smooth,
in-phase transfer back to utility power without interruption of service to the load. The battery
charging circuit then activates to recharge the batteries in preparation for the next power
outage.
2.0 Theory of Operation
2.1 AC (Line) Operation
During AC line operation, utility power is routed into the primary winding of the ferroresonant
transformer through the contacts of the transfer isolation relay. At the same time, power is
directed to the rectifier circuitry in the inverter which provides power for the control circuitry.
The bidirectional inverter also serves as a battery charger during AC line operation. The
ferroresonant transformer and an AC capacitor form the resonant tank circuit, which provides
excellent noise and spike attenuation, output short circuit current limiting, and output voltage
regulation. The ferroresonant transformer produces a quasi square wave output which
resembles a rounded square wave.
To minimize the possibility of the transformer entering unstable operation, the GMX Power Supply
requires a minimum load of at least one ampere connected to the output. Unstable transformers will
self-correct as soon as a load of one ampere or greater is connected to the power supply.
CAUTION!
The duration of battery-backed standby operation depends upon the type and number of batteries and the
load on the power supply.
NOTE:

19
017-932-B0-001, Rev. A
2.0 Theory of Operation, continued
2.3 Charger Operation
The GMX Power Supply uses a three-stage, temperature-compensated battery charger.
During AC line operation, the inverter winding on the ferroresonant transformer feeds the
charger circuit which provides BULK, ACCEPT, and FLOAT charge voltages to the batteries.
Charger Modes:
BULK charge is a “Constant Current” charge. Ten amps is the maximum the charger is
capable of delivering. As the charge is returned to the batteries, their voltage increases
to a specific threshold (2.27VDC per cell). This cycle ends when the charging current into
the batteries becomes less than 0.5A.The charger then switches to ACCEPT mode. The
BULK charger mode generally returns the battery charge state to 80 percent of rated battery
capacity.
ACCEPT charge is a “Constant Voltage” charge. This voltage, 2.40VDC (adjustable) per
cell, is temperature-compensated to ensure longer battery life and proper completion of the
charge cycle. This cycle is complete when the charging current into the batteries becomes
less than 0.5A, or approximately six hours from the time ACCEPT mode was entered. When
the batteries are fully recharged the charger switches to the FLOAT mode of operation.
FLOAT charge is a temperature-compensated “pulsed voltage” charge, averaging about
2.27VDC (adjustable) per cell. During FLOAT mode, the batteries are fully charged and ready
to provide backup power. The charger provides a small maintenance charge to overcome the
batteries self-discharge characteristics and other minor DC loads within the power supply. As
the battery voltage reaches the “full charge” level the time delay between pulses increases.
The cell voltage is temperature-compensated at -0.005VDC per cell per degree Celsius
(adjustable) to ensure a safe battery cell voltage and maximize battery life. The temperature
compensation is limited to a minimum of 2.20V per cell and a maximum of 2.50V per cell.
Fig. 2-1, Charger Modes
1
2
3
4
5
6
7
8
9
10
2.15
2.25
2.05
2.40
0
Volts Per Cell
Charger Current
Bulk Accept Float

20 017-932-B0-001, Rev. A
2.0 Theory of Operation, continued
Power Transformer
Blue/White
White
6
5HS2
HS3
J4
HS1 HS4
P5
Red Red
Black
Battery Connector
1 2
Chassis Ground Stud
Fan
J2
J1
J1 J3 J4 J2
34-pin Ribbon Cable Assy
Status Monitoring
Status Monitoring
Micro Board
16-pin Ribbon Cable Assy
Ov Out
Chassis Ground Stud
P13
P11
J1
K1, Isolation Relay
MOV
MOV
MOV
RV1
RV3
RV2
K3, Tap Switching Relay
Aux, Output Fuse
K2, Tap Switching Relay
Power Distribution Board
Terminal Block
Input Winding
Output Winding
Inverter Winding 6
5
7 8
9
10
11
[ 87V ]
[ 63V ]
LRI +
LRI -
VOUT +
VOUT -
GND
87V 63V
TAP SEL
1 2 3 4 5 6 7 8
1 2 3 4
P10
P12
P19
P18
[4] [3]
[2] [1]
Aux AC Output
1 2
IEC Input Connector
Brown Blue Green
1 2 3
Chassis Ground Stud
P5 P4 P3 P1 P8 P20 P9 P2 P7 P6 P24 P23
Resonant Capaciter
Oil Cap
Oil Cap
Inverter PCBA
Battery Temperature Probe
Fig. 2-2, GMX Block Diagram