A B C D E F G H I K L M N O P R S T U V W

A

AC (Alternating Current) An electric current that reverses direction in a circuit at regular intervals.

Accuracy The variation between the specified delay time and the Actual Time value, given in percent of specified delay. [(Actual Time – Specified Delay Time) / Specified Delay Time)] x 100.

Actual Time The actual delay of a given device with sufficient OFF time to input voltage to permit full recovery of the timing interval. The resulting average of a group of consecutive time delay readings (excluding the first) may be used to determine the Actual Time. Five cycles should be considered adequate for the determination.

Ambient Temperature Temperature of the air which encircles an object.

Ampere (Amp) The basic unit of electric current.

Arc A luminous discharge of electric current crossing a gap between two electrodes either through the air or over an insulated surface. It is deleterious to electromechanical switches, limiting contact life.

B

Break The moment and/or location at which a series circuit is opened and made discontinuous.

Brownout A condition in which the supply voltage is insufficient to power the load.

C

Circuit A closed path followed or capable of being followed by an electric current.

Closure The moment and/or location at which two contacts meet to complete a circuit.

Conductor A substance or medium that conducts heat, light, sound, or especially an electric current.

Contact Chatter (Contact Bounce) Occurs when an electromechanical switch is in the process of making connection in a circuit; for a brief time period, the contacts will bounce together until they are fully seated.

Contacts Electromechanical components that make or break a connection between two conductors that permit a flow of current.

Controller A regulating mechanism, as in an electric device used to control a particular process based on input parameters.

CSA Canadian Standards Association (Testing Laboratory for products sold in Canada.)

Current The amount of electric charge moving in a conductor past a specified circuit point within a given time. The basic unit is the ampere.

Cycle A single complete execution of a periodically repeated event or a periodically repeated sequence of events.

D

De-energize To remove power from a device.

Delay To postpone an event until a later time.

Delay On Break (Off Delay) A particular type of timing function whereby the OFF event is delayed after a start circuit is opened.

Delay on Make (Delay On Energize, On Delay) A particular type of time function which delays the ON event upon initial application of power to the timing device.

Dielectric Breakdown The voltage potential at which the insulating properties of a non-conductor will break down and conduct current. Measured in Kilovolts.

DC (Direct Current) An electric current flowing in one direction (constant polarity), as opposed to Alternating Current.

DPDT (Double Pole Double Throw 2 Form C Contacts) A type of contact configuration which consists of two isolated sets of contacts operating simultaneously. Each contact set consists of a Common contact, Normally Open contact, and a Normally Closed contact. In relay nomenclature, the states of the contacts are given with the relay coil unenergized.

E

Electricity A basic phenomenon in nature which involves the movement of electrons in a medium. This movement of electrons or electric current is considered a source of power.

Electromotive Force (EMF) Difference in electrical potential measured in volts.

Encapsulant A compound, typically epoxy or silicone elastomer, used to envelop and seal components in an electronic circuit.

Energize To apply power to a device.

External Adjustment A remotely located component or device which is used to alter an input or output parameter on a controller.

F

Factory Calibration To adjust a controller during the manufacturing process to specific points in order to meet the operational specifications.

Factory Fixed Fixing a particular control parameter during the manufacturing process to make it nonadjustable in the field.

Frequency The number of repetitions within a given time of a complete wave form, as of common line voltage with typical frequencies of 50 or 60 cycles per second. See Hertz.

Full-wave Rectified AC Alternating Current changed to Direct Current utilizing both the positive and negative portions of the AC sine wave.

G

Ground The point of an electric circuit that is at a zero volt potential with respect to the earth.

Guaranteed Range The range of operation of a controller or controlled parameter which the manufacturer specifies reliable consistent operation.

H

Half-wave Rectified AC Alternating Current changed to Direct Current utilizing only the positive or negative portion (not both) of the AC sine wave.

Heat Dissipation Because all electrical devices offer resistance to the flow of current, heat is generated when current flows through this resistance. This undesired heating effect is a function of the device resistance and the amount of current flowing through it. Heat sinks are used to cool high current devices, thereby dissipating the heat generated.

Heat Sink A device which possesses low thermal resistance in order to effectively absorb and dissipate heat.

Heat Sink Compound A compound used to assure good thermal connection between a heat dissipating device and a heat sink.

Hertz A unit of frequency named after Heinrich R. Hertz (1857-1894) which is equal to one cycle per second.

Holding Current In solid state switching devices there is a point at which the current flow is insufficient to maintain conduction. Holding current is specified as the minimum current through the device, across the operating temperature range, that will maintain conduction.

Horsepower (hp) A unit of power in the U.S. Customary System, equal to 745.7 watts or 33,000 foot-pounds per minute. Electrical motors are rated in horsepower, so accordingly, devices designed to control motors are also rated in horsepower.

Humidity Water vapor content in the air. In percent Relative Humidity, it is a measurement of the actual water vapor content of a unit volume relative to what the maximum amount of water vapor the same volume can contain at a given temperature.

Hysteresis The failure of a property that has been changed by an outside force to return to its original value when the cause of the change is removed. Some hysteresis is designed into controller circuits because it prevents noise from causing false triggering.

I

Incandescent Load From a switching perspective, the incandescent load represents an initial inrush current of up to 10 times the steady state rating.

Inductive Load An inductive load opposes any change to circuit current. Devices such as motors, solenoids, relay coils, valves, and contactor coils are all inherently inductive loads. The current waveform is always lagging the voltage waveform in an inductive load; because of the phenomena, certain factors must be taken into account when working with this type of load. An inductive load can exhibit an inrush current of up to 5 times its normal running or steady state current when energized. When power is removed from the inductive load, high voltage transients are generated due to the collapsing magnetic field, and this can cause arcing across contacts or a malfunction, and/or damage to electronic circuits.

Initiate Time (Start Time) The minimum time of a switch closure or voltage pulse applied to a start switch input of a controller which will activate the control function.

Input Voltage The voltage source applied to the controller input terminals which is used to power the controller while it is performing its function.

Inrush Current The peak value of current which a load requires when first being energized. Certain types of loads (e.g., lamps, motors) will draw a larger initial current because their impedance is lower at startup than during steady state operation.

Isolation No electrical connection between two or more circuits.

Insulation Resistance The degree of non-conductance of an insulator, measured in Megohms.

Insulator A material that insulates, particularly a nonconductor of electricity, heat, or sound.

Interval A period of time between events.