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I) Overview
The PM Series Power Module is a uniquely adaptable
communication equipment power source which
functions as either power supply or battery charger
for 12, 24 or 48 volt d.c. systems positive, negative or
floating ground. Power Modules may be employed
singly or in combina tion, enabling the installer to
scale the system output from 1000 to 6,000 watts per
rack. Units may be paral leled for N + 1 redundancy
and alarm contacts allow local or remote mon itoring.
An optional d.c. wiring quick connect kit allows easy
replacement of modules while the system as a whole
remains up and running (see section V-A).
Power Modules may be used separately as a power
source, or they may be integrated with NEWMAR's
Power Function Manager (model PFM-400; rated to
400 amps maximum) to greatly expand the system
capability with other functions such as digital output
monitoring, multiple load distribution and low
voltage disconnect. (Contact the factory for complete
information regarding the PFM-400.) Note: If the Power
Module is being installed as part of an integrated
system with the PFM-400 refer to the manual which
comes with that unit for all d.c. wiring instructions and
functional descriptions.
II) AC Power Quality and EMI Compatibility
A) AC Power Quality
Reliability is of prime concern when designing an
AC-DC power system for communication sites. Poor
AC input power quality can seriously impede system
reliability. In particular, transient disturbances on the
power lines can severely weaken or cause failure of
semi-conductors in power supplies and communication
gear. It is important that you know the input power
quality when installing the PM. Following is some basic
information on the subject:
Causes
Transients are characterized as a voltage pulse of high
energy and very short duration impressed upon the AC
wave form. These over voltage pulses can range from
1 to 100 times the normal AC voltage level and can
last for a fraction of a cycle to a few cycles.
Transient disturbances can be placed into two
categories:
- Lightning generated
- Equipment generated
A direct lightning hit on a utility power line will cause
a high energy voltage transient to travel in both
directions along the power line. This disturbance can
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California 92663
affect equipment hundreds of miles from the strike
point.
Equipment generated transient sources include utility
fault conditions and load switching as well as on-site
equipment such as pumps and air conditioning loads,
motors, phase control equipment.
Recommendations
All PM models requirements for transient withstand
capability. The AC power source should conform to this
specification to ensure reliable power supply operation.
If the power source quality is suspect or unknown, it
is recommended that an AC power quality survey be
conducted by a power quality consultant or power
conditioning firm. Corrective measures may include
lightning suppressors, line conditioners and filters.
An AC transient suppressor is recommended for
installations in third world countries and sites that
are subject to nearby lightning strikes or transients
caused by nearby motor contactors, air conditioning
compressors, etc.
B) EMI (Electro-Magnetic Interference) Considerations
The PM Series Power Modules employ switch-mode
technology to con vert AC to DC. They are designed
to produce minimal EMI levels when operating
(compliant to International Standards EN55022
(CISPR22) EN61000-3-2,3. Although the level of
EMI produced may be acceptable for most radio
applications, some installations may not even tolerate
what little EMI is produced.
Analog microwave and other extremely sensitive radio
sites may require additional input/output filtering and
careful installation. In some cases linear power supplies
(also available from NEWMAR) should be considered,
as they emit lower EMI (although they are more
susceptible to "brown-outs" or voltage sags and high
input voltage).
C) Other Factors
Some of the various factors which must be considered
when discussing electrical interference include the
following:
- RF Signal strength
- Ground loops
- Power and signal cable routing proximity
- Power supply and radio mounting locations
- Antenna, signal, and power grounds
Phone: 714-751-0488
Fax: 714-957-1621
E-Mail: techservice@newmarpower.com
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