Industry Glossary

To help answer questions you might have about UPS systems, batteries, standby generators, or other technical terminology, we’ve put together this glossary for you.

A | B |C |D | E | F | G | H | I |J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

Active power	In a DC circuit or in an AC circuit whose impedance is pure resistance, it is the product of root mean squared voltage and the root mean squared current expressed in watts. Also referred to a True or Real power.
Apparent power	Expressed in volt-amps, it is the product of the applied voltage and current in an AC circuit. As the power factor is not included in the calculation, it is not the true power (which is expressed in watts).

Burn-in	Testing a UPS at a predetermined power level for a predetermined time period
BMS	Building Management System. Also known as Building Automation System (BAS). A computerized system installed in buildings that controls and monitors the building's mechanical and electrical equipment such as ventilation, lighting, power, fire systems, and security systems. This can also refer to a Battery Management System used for controlling batteries. These systems help to prevent adverse battery states and monitor and extend battery life.

Burn-in

Testing a UPS at a predetermined power level for a predetermined time period

BMS

Building Management System. Also known as Building Automation System (BAS). A computerized system installed in buildings that controls and monitors the building's mechanical and electrical equipment such as ventilation, lighting, power, fire systems, and security systems. This can also refer to a Battery Management System used for controlling batteries. These systems help to prevent adverse battery states and monitor and extend battery life.

Capacitor	In a DC circuit or in an AC circuit whose impedance is pure resistance, it is the product of root mean squared voltage and the root mean squared current expressed in watts. Also referred to a True or Real power.
Catcher system	Expressed in volt-amps, it is the product of the applied voltage and current in an AC circuit. As the power factor is not included in the calculation, it is not the true power (which is expressed in watts).
Chopper circuit	Converts fixed dc input voltage to a variable dc output voltage directly.

D

DCIM	Data Center Infrastructure Management. The synchronization of data center facility management with information technology made available by electronic equipment signaling
De-rating curve	Reducing a UPS module operating characteristics due to a set of circumstances. Typically due to load power factor, altitude, or operating temperature.
Downtime	A measure of time that a computer, machine, process, operation, is not running, not working, and unavailable.

ECO mode	An energy saving operating mode of a double-conversion online UPS. However, this operating mode is often similar to Standby or Line Interactive models of smaller single phase UPSs. As the incremental energy savings over a highly efficient true online double conversion UPS is small and the risks of being exposed to unprotected utility power are high, customers that understand the high costs of downtime usually don’t operate their uninterruptible power supplies in ECO mode.
Efficiency	The useful power output of an electronic component or system divided by the total electrical power it consumes. For critical power devices such as UPS, typically expressed as a %.

ECO mode

An energy saving operating mode of a double-conversion online UPS. However, this operating mode is often similar to Standby or Line Interactive models of smaller single phase UPSs. As the incremental energy savings over a highly efficient true online double conversion UPS is small and the risks of being exposed to unprotected utility power are high, customers that understand the high costs of downtime usually don’t operate their uninterruptible power supplies in ECO mode.

Efficiency

The useful power output of an electronic component or system divided by the total electrical power it consumes. For critical power devices such as UPS, typically expressed as a %.

FAT	Factory Acceptance Test
Firmware	Software that resides on a hardware device. It typically resides in ROM (Read Only Memory), and can be updated by deleting a previous version and replacing with a more current one.

G

No available industry glossary starting with letter 'G'

H

Harmonics	In a DC circuit or in an AC circuit whose impedance is pure resistance, it is the product of root mean squared voltage and the root mean squared current expressed in watts. Also referred to a True or Real power.
Hyper-scale data center	A data center that has the physical infrastructure and distribution systems in place to support the capability to greatly scale computing tasks and the financial power and revenue sources of companies that require such hyperscale systems.

I

IFC608	International Fire Code – stationary storage battery systems
IGBT	Insulated Gate Bipolar Transistor; An electronic switching device with 3 terminals used for controlling power flow through a circuit.

No available industry glossary starting with letter 'J'

kAIC	kilo-Amperes Interrupting Capacity. Circuit breakers used in power backup systems typically include a kAIC rating, indicating the maximum amount of current that the circuit can be protected against. If a circuit breaker is installed with a kAIC that is too low for the circuit, it may not sufficiently protect the circuit from damage if overloaded.

Line Interactive UPS	Similar to the Standby UPS the Line Interactive UPS has a transfer switch that opens when the input power fails so that power flows from the battery to the UPS output. The DC battery-to-AC power converter (inverter) however is always connected to the output of the UPS which provides additional filtering and yields reduced switching transients when compared with the Standby UPS topology.
Lithium Ion batteries	Rechargeable batteries whereby lithium ions move from the positive electrode to the negative electrode during charge and back when discharging.

Maintenance bypass	Also known as a wraparound bypass, it enables the UPS to be isolated for maintenance or repair without interrupting power to the load.
Megapod	Expressed in volt-amps, it is the product of the applied voltage and current in an AC circuit. As the power factor is not included in the calculation, it is not the true power (which is expressed in watts).

NiCad Battery	NiCad stands for Nickel Cadmium, a reference to the electrodes on this type of battery being made of nickel oxide hydroxide and metallic cadmium. NiCad batteries are rechargeable batteries and offer good cycle life and performance.

Offline UPS	In this type of UPS, the load is directly connected to the incoming AC power supply, subjecting the load to any power fluctuations present in the raw power source. In the event of main power failure, the inverter turns on and power is supplied to the load from the backup power supply (i.e, batteries).
Online UPS	In this type of UPS, the inverter is always on, supplying a consistent and clean supply of power. When main power supply is present, it provides power to the inverter section while also charging the batteries.

PDU	Power Distribution Unit; distributes power to servers and networking equipment within a data center.
PUE	Power Usage Effectiveness, PUE is the inverse of the total efficiency in which a data center operates. This takes in to account he input to the data center. The ideal PUE is 1.0.

No available industry glossary starting with letter 'Q'

Reactor	An electromechanical device generally used for improving the voltage profile of transmission.
Real Power	See Active Power.

S

SCADA	Supervisory Control And Data Acquisition
SKPM	Solenoid Key Panel Mounted – relative to a trapped key interlock system

TCO	Total Cost of Ownership. Often performed for large UPS purchases this is the sum of the initial capital expense as well as all of the estimated operating expenses that that will be incurred over the expected operating life including preventative maintenance, fan replacement, capacitor replacement, and battery replacement.
Thermal runaway	Thermal runaway occurs in situations where an increase in battery temperature changes the conditions of the battery in a way that causes a further increase in temperature, often leading to a destructive result. It is a kind of uncontrolled positive feedback.

U

UL1778	UL (Underwriters Laboratories) Standard for Uninterruptible Power Supplies
UL924	UL (Underwriters Laboratories) Standard for Safety of Emergency Lighting and Power Equipment

V

Virtual neutral	Mitsubishi's proprietary technique for ensuring the UPS operates without electrically floating. This system also provides a means for harmonic mitigation and fault detection.
VRLA batteries	Valve-Regulated Lead Acid; sometimes referred to a seal lead acid or gel cell.

No available industry glossary starting with letter 'W'

No available industry glossary starting with letter 'X'

No available industry glossary starting with letter 'Y'

Z

No available industry glossary starting with letter 'Z'

0-9

2-level inverter topology	A 2-Level inverter topology refers to the number of steps in the UPS output inverter. The inverter uses the DC-link voltage to create a sine wave by switching the DC voltage in either of two modes, on or off.
3-level inverter topology	A 3-Level inverter topology refers to the number of steps in the UPS output inverter. The inverter uses the DC-link voltage to create a sine wave by switching the DC voltage in either of three modes, on, half voltage or off. Taping the middle of the capacitor bus creates the half voltage step.