Effective Power - In AC measurements, effective power (measured in watts) equals the product of voltage, current and power factor (the cosine of the phase angle between the current and the voltage).

Frequency Shift Keying (FSK) - Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK (BFSK). As suggested by the name, BFSK uses two discrete frequencies to transmit binary (0's and 1's) information. With this scheme, the "1" is called the mark frequency and the "0" is called the space frequency.

Full Scale (F.S.) - The specified maximum value of the input quantity being measured that can be applied to a device without causing a change in performance beyond the specified tolerance.

Full Scale Output - The specified maximum output value for which the stated accuracy condition applies.

GOSS - Grain Oriented Silicon Steel

Hall Effect - The Hall-effect is based upon the principle that a magnetic field applied perpendicular to a current will create a proportional Hall voltage perpendicular to the two fields. This technology allows; contactless sensing (sensing either an external magnet or a ferrous object) and non-intrusive current sensing. Hall-effect sensors are used for highly accurate gear-tooth sensing, direction detection, linear sensing, speed sensing, position sensing and contactless switching.

HART® Protocol - The HART protocol uses Frequency Shift Keying (FSK) on the Bell 202 1200 baud data communication standard to superimpose digital information on a conventional two wire 4 to 20mA analog signal. This enables two way communications between the host (master) device and the field instrumentation without interfering with the underlying analog signal. The HART protocol has become widely used in the process control industry. The protocol is maintained by an independent organization, the HART Communication Foundation.

Hertz (HZ) - Unit of frequency equal to cycles per second.

Hysterisis - An error resulting from the inability of an electrical signal or mechanical system to produce identical readings or position when approached slowly from either direction. Also referred to as deadband.

IEC 60044-1 - International Electrotechnical Commission "Instrument Transformers - Part 1: Current Transformers" standard. This standard covers the requirements and tests necessary for current transformers for use with electrical measuring instruments and electrical protective relays. The standard is applicable for electrical measuring instruments and electrical protective relays at frequencies from 15HZ to 100HZ.

Impedance - The opposition in an electrical circuit to the flow of alternating (AC) current. Impedance consists of ohmic resistance (R), inductive reactance (L), and capacitive reactance (C).

Inrush - The initial surge of current through a load when power is first applied. Lamp loads, induction motors, solenoids, contactors, valves, and capacitive loads all have inrush currents higher than the normal running or steady state currents. Resistive loads, such as heater elements, do not exhibit inrush.

Instrument Transformer - A transformer which is intended to reproduce in its secondary circuit, in a definite and known proportion, the current or voltage of its primary circuit with the phase relations substantially preserved.

Isolation - To be electrically separate. A measure of the strength of the dielectric providing the electrical isolation or separation.