All solid - state timer – A timing device with no moving parts to accomplish load switching.

Ambient temperature – The temperature of the air surrounding a timer under normal operating conditions.

CMOS IC timing - An integrated circuit timing control method using a self-contained oscillator, digital counter and output circuit to drive relays or trigger solid state outputs. Characterized by very low power consumption and immunity to voltage fluctuations.

De-Energization – Also De-Energize. The removal of power from a circuit or electrical device.

Dielectric strength – The voltage insulation integrity of any part of a timer’s circuitry versus the timer’s metal enclosure and the relay output contact terminals. UL-CSA units have a higher dielectric strength because of the more stringent insulation requirements.

Digital circuitry – Electronic logic circuitry that operates by pulse counting and switching. Very accurate method of controlling timing devices.

Energize – To apply rated voltage to a circuit or device, such as a coil of a relay, etc., in order to activate it.

External initiate switch – The method of actuating the timing sequence with a switch isolated from input and output. Used on Delay On Break and Single Shot timers.

Factory set – A timer that has a fixed time delay built in — not variable.

False transfer – Sometimes called False Operation or False Output. A momentary closing of the relay output contacts that occurs on certain types of timers if the input voltage is removed before completion of the time delay period. Applies to RC timers only.

False triggering – A premature switching in a timer caused by line voltage transients or brief power interruptions.

First cycle error– A large additive step to a desired time period which is produced by certain types and designs of timers. Usually observed on the first cycle after an extended rest period. Frequently not mentioned in specifications of repeatability. This characteristic does not apply to digital timers.

Fixed conditions – Conditions of constant temperature and voltage during which timer repeatability is measured and stated.

Fixed external – A timer that has two terminals across which a resistor can be placed to set the delay of a timer permanently.

Form C contacts – A term used to describe one set of Normally Open (NO) and Normally Closed (NC) contacts.

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Heat sinking – A means of removing heat from a power handling electronic device using finned radiators or metal to metal thermal conduction.

Inductive load – The device that a timer controls that initially resists a change in current, typically a coil, such as a solenoid, contactor or relay.

Input voltage – Term used to describe the operating voltage of a timer. Can be the same or different than output voltage depending on timer.

Input voltage break – Removing the input voltage to a timer for a brief interval, typically less than one second, to accomplish a reset in time or function.

Input voltages – A selection of AC or DC voltages over which a timer can be specified to operate.

Inrush – The initial surge of current that the output of a timer handles when switching certain loads, such as tungsten lamps, motors or capacitive loads.

Integrated circuit – Many electronic components doing complex functions in a single package. (See CMOS)

Load – Any device that is controlled by another. Generally expressed as a current or power requirement, i.e., 10 amp load — 300 watt or volt ampere load.

Magnal base – An 11 pin tube type base with an aligning key in the center to insure correct insertion of the base into a socket. Often erroneously called 11 pin octal.

Millisecond – One, one thousandth of a second — 1/1000 sec.; .001 Sec.

MOSFET – A transistor made with metal oxide semiconductor technology that can switch large amounts of current with a small control signal. Very reliable and stable in high temperature applications.

Nominal voltages – A single value of voltage falling within an allowable operating range, e.g., 120 volts as opposed to the range of 102 to 138 volts.

Normally closed (NC) contacts – Relay contacts that are closed when the relay is in a de-energized condition.

Normally open (NO) contacts – Relay contacts that are open when the relay is in a de-energized condition.

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Octal base – An 8 pin tube type base with an aligning key in the center to insure proper insertion of the base into a socket.

Ohm, K ohm, megohm – Units of resistance. Ohm is basic unit. Practical units for timing purposes are K ohm (1,000 ohms) and megohm (1 million ohms).

Operating temperature – The temperature range over which a timer will operate and maintain its specified performance criteria.

Operating voltage – The voltage range over which a timer will operate and maintain its specified performance criteria.

Output – The part of a timing device that accomplishes the switching action. Can be a relay or solid state device. Rated by current carrying capacity and maximum voltage allowed.

Polarity protection – Sometimes called Reverse Polarity Protection. The protective circuity incorporated in a timer in the event a wrong DC input voltage polarity is applied. Protected timers will not function or be damaged in such an occurrence.

Potentiometer – A variable resistor controlled by a rotating shaft. On timers it is adjusted by a knob to vary the delay time.

Power leakage – A term used to describe the current that flows through a solid - state output when it is off. A function of voltage and temperature.

Power requirements – The maximum power required for operation of a timer at a normal voltage. This is expressed in watts or volt-amperes.

Quick connect (QC) terminals – Blade type male terminals 3/16" or 1/4" in width. On relay bases can be plugged into a socket or individually terminated with matching female (Amp Type) connectors.

RC timing – A basic timing circuit consisting of a resistor (fixed or variable) in series with a capacitor. When a voltage is applied to the resistor-capacitor circuit, the voltage across the capacitor increases as a function of time. At a determined voltage level a solid-state trigger device fires or conducts to energize a relay. Many variations of the RC timing circuit are available.

Re-cycle effect – Refer to “First Cycle Error”

Re-cycle time – The non-timing period of a timer between timing cycles.

Relay output contacts – Load switching contacts on the timer internal relay.

Relay output form:

  • DPDT — Double Pole, Double Throw. A relay with two separate poles, each with a Normally Closed (N.C) and Normally Open (N.O.) contact.

  • DP(1)DT(1)ST — Double Pole, Double Throw, Single Throw. A two pole relay, one side is Double Throw, the other is Single Throw.

  • SPDT — Single Pole, Double Throw. A one pole relay, Normally Closed (N.C.) and Normally Open (N.O.) contacts.

  • SPST — Single Pole, Single Throw. A one pole relay, either Normally Closed (N.C.) or Normally Open (N.O.). Also describes an All Solid State output as on In-Line cube timers.

  • 3PDT — Three Pole, Double Throw. A relay with three separate poles, each having Normally Closed (N.C.) and Normally Open (N.O.) contacts.

Relay pull-in time – The time required for the timer internal relay to switch from its de-energized position. Specified in milliseconds (msec).

Relay timer – A timing device with a set or sets of mechanical contacts controlled by electronic circuitry. (See Relay Output Form)

Repeat accuracy – The maximum variation in a time period, expressed in a ± percentage from the first timing cycle to successive timing cycles. This is within the operating voltage and temperature range.

Reset time – The length of time that input power must be interrupted or initiate switch must be operated to initiate another cycle in a timer.

Reset/recycle time – The minimum period of time in milliseconds (msec) required to turn a timer OFF and/or ON again for a new cycle without loss of repeat accuracy.

Resistive load – The device that the timer controls that has no inductance or capacitance; example is a heating element. 100% power factor.

Resistor – A device that opposes electric current flow, measured in ohms. In timers, used to set charge rates for timing capacitors or frequency in digital oscillators.

Solid state – A general term for semiconductor electronic circuitry. In timers refers to RC and CMOS timing circuits. In switching (output) applications to SCRs — TRIACs, MOSFETs.

Square base – Used in reference to a .187 QC Blade Terminal/relay with essentially a square panel. The terminals are often called Blade, Fast-On, QC (Quick Connect), Spade, Tab, etc. It is a flat male terminal .187 wide x .020 thick properly spaced in a panel for plug-in mounting. Pierced holes in the terminals accommodate solder wiring.

Storage temperature – The maximum temperatures to which a timer circuit can be exposed in the storage (non-operative) state and thereafter provide reliable performance within the operating temperature range.

Surge – A rapid increase in voltage or current by a power source. Can destroy a timer if not limited.

Temperature range end limits (Tolerance) – The minimum and maximum temperature which can not be exceeded during storage or operation in order to assure reliable operation of device.

Timing ranges – Time delay periods available for a particular type timer.

Timing resistor – See Resistor

Transient Protection – The prevention of malfunction or failure of a timer due to power line transients. Protection is usually provided by proper circuit design and/or suppression devices and is specified as a maximum voltage and time duration.

Transients – Spurious voltage spikes on a power line that can produce false triggering impulses and/or cause insulation and component breakdowns and failures. Usually caused by load switching or inductive devices.

Triac – A solid state switching device that controls an A.C. load, used in place of a relay in a timer. v

Variable external – A timer that is supplied with a timer adjusting potentiometer separate from the main unit. Two terminals for connecting wires are on the timer.

Variable integral – A timer that has a means of time adjustment as part of its construction, such as a knob and dial.

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