Inverter (on-line) - UPS configuration in which the inverter is in series mounted between the mains and the load. All power drawn by the load passes via the inverter. This is the only configuration used for high outputs.
Internal Resistance (IR) - The opposition exhibited by a circuit element to the flow of direct current (d.c.). In a cell, the internal resistance is the sum of the ionic and electronic resistances of the cell components.
Distortion (total) - Ratio between the rms value of all harmonics of a non-sinusoidal alternating periodic value and that of the fundamental. This value may also be expressed as a function of the individual distortion of each harmonic Hn= Yn /Y1.
Harmonics (current and voltage) - All alternating current which is not absolutely sinusoidal is made up of a fundamental and a certain number of current harmonics which are the cause of its deformation (distortion) when compared to the theoretical sine-wave. For each current harmonic of order n and an rms value In, there is a voltage harmonic with an rms value Un. If Zsn is the voltage source output impedance for the harmonic of the nth order, then - Un = Zsn x In
Temperature Cutoff (TCO) - A protective or safety device (e.g., thermostat, PTC, etc.) which senses temperature (e.g., in a battery) and opens or cuts off the electrical circuit if the specified temperature is exceeded, thus preventing a further rise in temperature due to the charge or discharge of a battery.
Positive Temperature Coefficient (PTC) - A thermally reactive device which becomes highly resistive at a specific temperature or current.
Power factor (l) - Ratio between the active power P supplied to a load and the apparent power S supplied to said load by an AC power supply.
