advanced battery management--A three-stage charging system
designed to prolong the service life of UPS batteries.
By charging the batteries only when necessary, battery
life is significantly improved. Charging stage one: quickly
recharges battery to approximately 90% of capacity. Charging
stage two: fully charges the battery to 100%. Charging
stage three: rest mode prevents overcharging. Charging
stage one is initiated after a power outage or periodic
(A) or amp--The unit for the electric current; the flow
of electrons. One amp is 1 coulomb passing in one second.
One amp is produced by an electric force of 1 volt acting
across a resistance of 1 ohm.
(AH)--Quantity of electricity or measure of charge. How
many amps flow or can be provided over a one hour period.
Most batteries are rated in AH.
number of photovoltaic modules connected together to provide
a single electrical output. Arrays are often designed
to produce significant amounts of electricity.
charge - The second stage of three-stage battery charging.
Voltage remains constant and current tapers as internal
battery resistance increases during charging. (Ensures
alternating current (AC) - The type of electrical power
supplied by utilities or made when a generator is run.
The unique characteristic of this form of electricity
is that it reverses direction at regular intervals. For
example, 120 Vac 60 Hz. power reverses flow 60 times a
second, hence the rating 60 Hz. (cycles).
charge - The first stage of three-stage battery charging.
Current is sent to batteries at the maximum rate they
will accept while voltage rises to full charge level.
battery backup--A battery or a set of batteries in a UPS
system. Its purpose is to provide an alternate source
of power if the main source is interrupted.
battery capacity--The battery ampere-hour capacity at
full charge, standard temperature, and at a specified
(usually C10) discharge rate.
battery charger--A device or a system which provides the
electrical power needed to keep the battery backup fully
battery current limit--System voltage control that limits
the battery charge current to a preset value.
bi-directional converter--A device which changes (or converts)
alternating-current power to direct-current power and
blackout--A total loss of the AC utility (commercial power).
brownout--A reduction in the voltage of the AC utility
without complete loss of power.
buck and boost--A proprietary voltage regulation process
used when an overvoltage or undervoltage situation occurs
in the UPS. Undervoltage is boosted to make the voltage
greater, and overvoltage is bucked to reduce it. The result
is less reliance on the UPS battery, extending overall
bus voltage--The actual voltage supplied to the load as
measured at the bus bars.
bypass--A circuit used to change the path of the electrical
power so that it goes around (or bypasses) its normal
path. In the UPS, the bypass circuit is used to route
the power around the major electronics in the UPS so they
can be serviced without power interruption.
basic unit of a photovoltaic panel or battery
controller--An electronic device which regulates the voltage
applied to the battery system from the PV array. Essential
for ensuring that batteries obtain maximum state of charge
and longest life.
- The rate of flow of electrical charge. The flow of amps
is often expressed as current.
clean power--Electrical power which has been conditioned
and/or regulated to remove electrical noise from the output
discharge--Discharging a battery to 20-percent or less
of its full charge.
current (DC)--A type of current which never reverses its
direction. Since the current flows in only one direct
on, the average value of the current cannot be zero unless
the current has stopped flowing.
double-conversion--A UPS design in which the primary power
path consists of a rectifier and inverter. Double-conversion
isolates the output power from all input anomalies such
as low voltage, surges and frequency variations by converting
AC to DC to AC. See Online UPS.
rate--The rate, usually expressed in amperes or time,
at which electrical current is taken from the battery.
current--A flow of electrons; electricity, amps.
grid--An integrated system of electricity distribution,
usually covering a large area. As in "off the grid".
liquid conductor of electricity. In batteries, usually
H2SO4, sulfuric acid, but may be any number of things.
Seawater is the most common electrolyte in the world -
and by suspending a zinc and a steel sheet in it, you
can get a little electricity.
ability to do work. Stored energy becomes working energy
when we use it.
density--The ratio of energy available from a battery
to its volume (Wh/1) or mass (Wh/kg). "watts to weight"
efficiency--The ratio of the output power from the UPS
to the input power from the utility. This shows the percentage
of the input power that is available as useful output
power. For example, a UPS that is 95% efficient delivers
95% of the utility power it receives to the load. The
remaining power takes the form of dissipated heat.
emergency shutdown--Used to instantly or quickly shutdown
all of the electrical power available to the UPS and the
load. An emergency shutdown device is usually used during
a crisis to prevent damage to the UPS and the load. Some
computer-room installations require a Remote Emergency
Power Off (REPO) capability as part of their security/safety
charge--Float charge is the voltage required to counteract
the self-discharge of the battery at a certain temperature.
float voltage--The set output voltage of the DC power
system (not including temperature compensation or other
frequency--The number of cycles (oscillation positive
and negative) completed in one second. Defined as Hertz
full load--The greatest load that a circuit is designed
to carry under specific conditions; any additional load
is considered an overload.
cell--A device that converts the energy of a fuel directly
to electricity and heat, without combustion. Because there
is no combustion, fuel cells give off few emissions; because
there are no moving parts, fuel cells are quiet.
- When used in reference to utility power, it refers to
a system of electrical transmission and distribution lines.
battery--Lead-acid battery in which the electrolyte is
composed of a silica gel matrix.
(PV system)--A PV system in which the PV array acts like
a central generating plant, supplying power to the grid.
(Hz.) - The frequency, or number of times per second,
that the flow of AC electricity reverses itself. Also
referred to as cycles (see alternating current).
high battery protection - A control circuit that disconnects
charge current flowing to battery(s) when voltage reaches
a dangerously high threshold. Prevents damage created
by excess gassing (or boiling) of electrolyte.
hydrometer - A simple device that measures the specific
gravity of battery electrolyte. Specific gravity readings
express state of charge/discharge of battery.
harmonic distortion--The presence of harmonics that change
the AC voltage waveform from a simple sinusoidal to complex
waveform. Harmonic distortion can be generated by a load
and fed back to the AC utility line, causing power problems
to other equipment on the same circuit.
that convert DC electricity into AC electricity (single
or multiphase), either for stand-alone systems (not connected
to the grid) or for utility-interactive systems.
current - The amount of electrical power required to keep
an inverter ready to produce electricity on demand.
isolation--The separation (often through the use of an
isolation transformer) of one section of a system from
undesired electrical influences of other sections.
(kW)--One thousand watts of electricity. Ten 100-watt
light bulbs use one Kilowatt of electrical power.
(kWh)--One kW of electrical power used for one hour. The
most common measurement of electrical consumption, most
grid connected electrical meters measure kW/h for billing
purposes. 1 kWh=3600 kJ.
line-interactive--A UPS containing an off-line inverter
that must transfer on during a blackout, but provides
faster transfer times than an off-line UPS. Power conditioning
and surge suppression are provided to protect the connected
light emitting diode (LED) - A device used to display
various status functions.
line loss - A voltage drop caused by resistance in wire
during transmission of electrical power over distance.
line-tie - An electrical system that is connected to a
utility distribution grid. For example, Trace SW line-tie
inverters are designed to connect to and interact with
load - Any device that consumes electricity in order to
operate. Appliances, tools, and lights are examples of
low battery protection - A control circuit that stops
the flow of electricity from batteries to loads when battery
voltage drops to dangerously low levels.
sine wave - An AC wave form (generated by many inverters)
that is a pulse width modified square wave. It consists
of a number of very small on/off steps rather than a fully
manual bypass switch (MBS)--A manually operated transfer
switch used to bypass the major electronics in the UPS,
so the UPS can be serviced without power interruption.
sporadic, or multi-frequency electrical signals that become
part of a transmission making the signal or information
more difficult to identify.
nominal system voltage--The DC output voltage generally
used to describe a type of system, usually 24 V or 48
unit of resistance to the flow of an electric current.
voltage (Voc)--The maximum possible voltage across a photovoltaic
cell or module; the voltage across the cell in sunlight
when no current is flowing.
oscilloscope - A device that displays the wave form created
by an electrical generating device such as a generator,
inverter, or utility.
overload/overcurrent protection - A control circuit designed
to protect an inverter or similar device from loads exceeding
its output capacity. (A fuse, for example, is an overcurrent
protection device.) All Trace inverters have internal
circuitry to protect themselves from overload/overcurrent
off-line UPS--A UPS type which feeds power to the load
directly from the utility and then transfers to battery
power via an inverter after utility drops below a specified
voltage. The delay between utility power loss and inverter
startup can be long enough to disrupt the operation of
some sensitive loads. Also called a standby UPS.
online UPS--A UPS in which the inverter is on during normal
operating conditions supplying conditioned power to the
load through an inverter or converter that constantly
controls the AC output of the UPS regardless of the utility
line input. In the event of a utility power failure, there
is no delay or transfer time to backup power.
outlet--Any point on a wiring system where current is
taken to supply electrical power for a load.
overvoltage shutdown (OVSD)--A protection method that
will shutdown any rectifier module with an output voltage
over a preset maximum value.
connection--A way of joining two or more electricity-producing
devices (i.e., PV cells or modules) by connecting positive
leads together and negative leads together; such a configuration
increases the current.
parallel wiring - A group of electrical devices, such
as batteries or PV modules, wired together to increase
ampacity, while voltage remains constant. (Two 100 amp
hour 12 Vdc batteries wired in parallel will form a 200
amp-hour 12 Vdc battery bank.).
parallel online UPS--Online UPS technology that provides
redundant sources of conditioned backup power so that
the critical load is protected even in the event of UPS
(PV)--Pertaining to the direct conversion of light into
(PV) array--An interconnected system of PV modules that
function as a single electricity-producing unit. The modules
are assembled as a discrete structure, with common support
or mounting. In smaller systems, an array can consist
of a single module.
(PV) cell--The smallest semiconductor element within a
PV module to perform the immediate conversion of light
into electrical energy (dc voltage and current).
(PV) panel--often used interchangeably with PV module
(especially in one-module systems), but more accurately
used to refer to a physically connected collection of
modules (i.e., a laminate string of modules used to achieve
a required voltage and current).
photovoltaic system - The components that form a solar
electric generating system, usually consisting of PV modules,
charge controller, circuit protectors (fuses or breakers)
factor--The ratio of the average power and the apparent
volt-amperes. Affected by the inductance and capacitance
of the load. A pure resistance, such as an electric heater
would have a power factor of 1.00.
(PWM) - A function of many of the newer charge controllers
and battery chargers which instead of applying a steady
DC voltage to the battery, sends out short pulses. The
width of the pulses varies with the battery state of charge.
voltage drop--The voltage developed across a cell by the
current flow through the resistance of the cell.
RS-232--Also called serial ports; a method of communicating
digital information in which the data bits are transmitted
sequentially over one line.
discharge--The rate at which a battery, without a load,
will lose its charge. This can vary considerably depending
on the type of battery and age. It can be as low as 3%
a month for a new AGM battery, and as high as 10% a week
for an older Lead-Antimony (industrial).
energy--Energy from the sun. The heat that builds up in
your car when it is parked in the sun is an example of
scalable UPS--A UPS that allows for expandability; for
example, enables a UPS to accommodate a larger load by
purchasing additional power modules.
single-phase power (1Ø)--Power that is provided
by a single source which normally includes one hot lead
and a grounded return line (neutral).
square wave--Output waveform generated by very basic,
low-cost UPSs. Functions adequately for less sensitive
loads, but may not provide acceptable quality input for
some types of electronic equipment.
start-on-battery--Enables user to power up UPS in the
absence of utility power.
surge--A transient (or momentary) wave of current, potential,
or power in an electric circuit.
wave inverter--The inverter consists of a dc source, four
switches, and the load. The switches are power semiconductors
that can carry a large current and withstand a high voltage
rating. The switches are turned on and off at a correct
sequence, at a certain frequency. The square wave inverter
is the simplest and the least expensive to purchase, but
it produces the lowest quality of power.
condition that afflicts unused and discharged batteries;
large crystals of lead sulfate grow on the plate, instead
of the usual tiny crystals, making the battery extremely
difficult to recharge.
series wiring - A group of electrical devices, such as
batteries or PV modules, wired together to increase voltage,
while ampacity remains constant. (Two 100 amp hour 12
Vdc batteries wired in series form a 100 amp hour 24 Vdc
sine wave - The output wave form of an electric generator
or utility. A smooth wave going above and below zero is
surge capacity - The amount of current an inverter can
deliver for short periods of time. Most electric motors
draw up to three times their rated current when starting.
An inverter will "surge" to meet these motor-starting
requirements. Most Trace inverters have surge capacities
at least three times their continuous ratings.
AC voltage up or down, depending on the application.
charge--A charge at a low rate, balancing through self-discharge
losses, to maintain a cell or battery in a fully charged
transfer switch - A switch designed to transfer electricity
being supplied to loads (appliances etc.) from one source
of power to another. (A transfer switch may be used to
designate whether power to a distribution panel will come
from a generator or inverter.)
temperature compensation--Adjustment of the rectifier
output voltage to provide the optimum charging voltage
for the battery. One of the components in system voltage
control, calculated by the Supervisory Module calculation
based on battery temperature.
terminal block--An insulating base equipped with terminals
for connecting secondary and control wiring. Used on hardwired
equipment, such as a UPS, when input plugs and output
receptacles are either impractical or unavailable.
three-phase power (3Ø)--Power that is provided
by a single source with three outputs with a phase difference
of 120 ° between any two of the three voltages and
transfer switch--A switch which will transfer current
from one circuit path to another without interrupting
the flow of the current.
transient--The fast radical change in a smooth sine wave
that occurs in both voltage and current waveforms during
the transition from one steady-state operating condition
trickle charge--With the trickle charging process, the
battery receives a constant voltage feeding a low current.
Constant use of this method dries the electrolyte and
corrodes the plate, reducing potential battery service
life by up to 50 percent.
two-phase power--Power which is provided by a single source
with two outputs which may be 180 degrees out of phase
or 120 degrees out of phase.
power system (UPS)--A system designed to automatically
provide power, without delay or transients, when the normal
power supply is incapable of supplying acceptable power.
Some UPSs also filter and/or regulate utility power.
UPS topology--Overall term describing the internal circuitry
of a UPS. There are three basic UPS topologies: standby
(off-line), line-interactive, and online.
dc Vmp--Voltage at maximum power
(V)--A unit of measure of the force, or 'push,' given
the electrons in an electric circuit. One volt produces
one ampere of current when acting a resistance of one
Volt-ampere (VA)--Voltage (V) multiplied by the current
(ampere); apparent power. For instance, a device rated
at 10 amps and 120 V has a VA rating of 1200 or 1.2 kVA.
thin sheet of semiconductor material made by mechanically
sawing it from a single-crystal or multicrystal ingot
(W)--The unit of electric power, or amount of work (J),
done in a unit of time. One ampere of current flowing
at a potential of one volt produces one watt of power.
shape of the curve graphically representing the change
in the ac signal voltage and current amplitude, with respect
Watt hour (Wh) - Electrical power measured in terms of
time. One watt hour of electricity is equal to one watt
of power being consumed for one hour. (A one-watt light
operated for one hour would consume one watt hour of electricity.)