1.7 Relay Terms and Definitions-Glossary
The following definitions do not include terms peculiar to mathematical
formulae, statistical analysis, relay reliability studies, and the like. Such
terms are defined in the appropriate chapter. When cross-references are
made, the preferred terminology is the one under which the definition
appears.
Dashpot. A device that employs either a gas or liquid to absorb energy
and retard the operation of the relay.
De-energize. To remove power from a relay coil.
Dielectric strength. VISO-The maximum allowable ac rms voltage
(50/60Hz)
which may be applied between two specified test points such as input-output,
input-case, output-case in solid state relays, and between current-carrying and
non-current-carrying metal members in electromechanical relays.
Disengage. A relay disengages at the instant it terminates a function
previously effected in a given output circuit.(IEC)
Disengaging value of the characteristic quantity The threshold value of
the characteristic quantity at which the relay disengages under specified
conditions.(IEC)
Disengaging ratio. The ratio of the disengaging value to the operating
value.(IEC)
Dropout, to drop out. A monostable relay drops out when it changes from
an energized to an unenergized condition. (IEC)
Dropout, time. See time, release.
Dropout value, measured. As the current or voltage on an operated relay
is decreased, the value at which all contacts restore to their unoperated
positions.
Dropout value, specified. As the current or voltage on an operated relay
is decreased, the value at or above which all relay contacts must restore to
their unoperated positions.
Dry reed relay. See relay, reed.
Duty cycle. A statement of energized and de-energized time in
repetitious operation; for example, 2 seconds on, 6 seconds off. Often
expressed as the energized percentage of total cycle time.
Dynamic contact resistance. A change in contact electrical resistance
due to a variation in contact pressure on a contacts mechanically closed (see
Figures 1.1 and 1.2); occurrence is during non-bounce condition.
Energization. The application of power to a coil winding of a relay.
With respect to an operating coil winding, use of the word commonly assumes
enough power to operate the fully unless otherwise stated.
Energized condition. The specified condition(s) of an appropriately
energized monostable relay. (IEC)
Energizing quantity. An electrical quantity (either current or voltage)
alone, or combined with other such quantities which when applied to a relay
under specified conditions enables it to fulfill its purpose.(IEC)
Energizing quantity, input. For an all-or-nothing relay: The energizing
quantity that the relay will respond to when that quantity is applied under
specified conditions. For a measuring relay: An energizing quantity which
either by itself constitutes the characteristic quantity or helps to
constitute it. (IEC)
Final actuation time. See contact, final actuation time.
Fixed contact. See contact, stationary.
Flux, leakage. That portion of the magnetic flux that does not cross the
the armature to pole-face-gap.
Follow, contacts. The force exerted by a movable contact against a fixed
contact when the contacts are closed.
Force, contact. The force exerted by a movable contact against a fixed
contact when the contacts are closed.
Form, contact. See combination, contact.
Frame. The main supporting portion of a relay, which may include parts
of the magnetic structure.
Freezing, magnetic. Sticking of the relay armature to the core due to
residual magnetism.
Frequency, operating. The rated ac frequency of the supply voltage at
which the relay is designed to operate.
Fulcrum (armature). See bearing, armature.
Gaging, relay contact. The setting of relay contact spacing to determine
the point in the armature's stoke at which specified contacts function.
Gap, armature The distance between armature and pole face.
Gap, buffer. The space separating the armature buffer and the movable
spring, or the space between the movable springs and buffers when the armature
is in its unoperated position.
Gap, contact. The distance between a pair of mating relay contacts when
the contacts are open.
Gap, heel. A gap or nonmagnetic separation in the magnetic circuit other
than between the armature and pole face. Generally, located between the heel
piece and pole piece of an ac relay.
Gap, hinge. See hinge gap.
Gap, residual. The thickness of nonmagnetic material in the magnetic
circuit between the pole face center and the nearest point on the armature when
the armature is in the fully seated position.
Gap, stud. See gap buffer.
Grass. See dynamic contact resistance.
Header. The subassembly that supports and insulates the leads passing
through the wall of a sealed relay.
Heel piece. The portion of a magnetic circuit of a relay that is
attached to the end of the core remote from the armature.
Hermetically sealed relay. See relay, enclosed.
Hesitation, armature. Delay or momentary reversal of armature motion in
either the pickup or dropout stroke.
Hinge, armature. Delay or momentary reversal of armature motion in
either the pickup or dropout stroke.
Hinge gap. Space between the armature and the frame at the hinge (allows
for armature to move without binding).
Hold value specified. As the current or voltage on an operated relay is
decreased, the value at or above which all relay contacts must restore to their
unoperated positions.
Homing. See relay, homing.
Housing. An enclosure or cover for one or more relays, with or without
accessories; usually provides access to the terminals.
Hum. The sound caused by mechanical vibration resulting from
alternating current flowing in the coil, or by unfiltered rectified
current.
Humidity, non-operating. That steady state humidity to which the relay
may be subjected without electrical malfunction or mechanical damage.
Humidity, operating. That steady state humidity to which the relay may be
subjected without electrical malfunction or mechanical damage.
Influencing quantity (factor). Any quantity (factor) likely to modify any
of the specified characteristics of a relay (e.g., pickup, dropping out,
accuracy, etc.). (IEC)
Initial actuation time. See contact initial actuation time.
Input. That portion of a relay to which a control signal is applied in
order to achieve the switching function (generally applied to solid state or
hybrid relays).
Insulation resistance. RISO The minimum allowable dc resistan
between
input and output of solid state relays and between contacts and coil for
electromechanical and reed relays.
Isolation. The value of insulation resistance, dielectric strength, and
capacitance measured between the input and outputs, input to case, output to
case, and output to output when applicable.
Lead, finish. The outer termination of the coil winding.
Lead, inside. See lead, start.
Lead, outside. See lead, finish.
Lead, start. The inner termination of the coil winding.
Leakage (max.off state current ID(rms)). The rms current
conducted by the
output circuit of the relay at maximum load voltage with zero input
voltage/current.
Level. A series of contacts served by one wiper of a stepping
switch.
Lifter, armature. See buffer, armature.
Limiting continuous thermal withstand value of an energizing quantity.
The highest value (rms if ac) of the energizing quantity that a relay can carry
continuously and under specified conditions, while satisfying the temperature
rise requirements. (IEC)
Limiting dynamic value of an energizing quantity. The highest value of
an energizing quantity that a relay can withstand under specified conditions of
wave form and duration without permanent degradation of the specified
characteristics due to the resultant dynamic effect. (IEC)
Limiting short-term thermal withstand value of an energizing quantity.
The highest value (rms if ac) of an energizing quantity that a relay can
withstand under specified conditions for a specified short time without
permanent degradation of the specified characteristics due to overheating.
(IEC) See rating, short time.
Load, contact. The electrical power encountered by a contact set in any
particular application.
Load, curve. The static force/displacement characteristics of the total
spring-load of the relay. (See Figure 1.15).
Magnet, blowout. A device that establishes a magnetic field in the
contact gap to help extinguish the arc by displacing it.
Make. The closure of open contacts to complete an electric circuit.
Mechanical shock, non-operating. The mechanical shock level (amplitude,
duration and wave shape) to which the relay may be subjected without permanent
electrical or mechanical damage (during storage or transportation).
Mechanical shock, operating. That mechanical shock level
(amplitude, duration and wave shape) to which the relay may be subjected
without
permanent electrical or mechanical damage during its operating mode.
Meter relay. See relay, instrument.
Minimum current. See current, intermediate.
Miss, contact. Failure of a contact mating pair to establish the
intended circuit. This may be a contact resistance in excess of a specified
maximum value.
Mounting plane. The surface to which the relay is fastened.
Nonbridging. See contact, nonbridging.
Nondropout, specified. See operating characteristics, hold value.
Nonfreeze pin. See residual.
Nonoperate, specified. See operating characteristics, nonpickup.
Nonpickup value, specified. As the current or voltage on an unoperated
relay is increased, the value which must be reached before any contact change
occurs.
Nonrelease, specified. See operating characteristics, hold value.
Normal condition. The de-energized condition of the relay.
Normal position. The de-energized position of contacts, open or closed,
due to spring tension, gravity, or magnetic polarity. The term is also used for
the home position of a stepping switch.
Normal sequence of operation. The intended contact operation sequence
built into a relay unaffected by wear or dimensional change. See gaging,
relay contact.
Offstate dv/dt. The application of both position and negative voltages
with maximum specified rate of rise to the output terminals.
Operate. A relay operates when sequentially it starts, it passes from an
initial condition towards the prescribed operated condition, and it
switches.(IEC)
Operate time. See contact operate time.
Operate value. See operating characteristics, pickup value.
Operate value, just. See operating characteristics, pickup value,
measured.
Operate value, must. See operating characteristics, pickup value,
specified.
Operating characteristics. Pickup, nonpickup, hold and dropout, voltage
and current.
Operative range of an input energizing quantity of an all-or-nothing
relay. The range of values of the given input energizing quantity for which
the relay, under specified conditions is able to perform its intended
function(s) according to the specified requirements. (IEC)
Operative range of an input energizing quantity of a measuring relay.
The range of values of the given input energizing quantity for which the relay,
under specified conditions, is able to perform its intended function(s)
according to the specified requirements. (IEC)
Output. That portion of a relay which performs the switching function
required. Generally applied to solid state and hybrid relays.
Output circuit. The whole of the electrically conductive parts within a
relay connected to the terminals between which the predetermined change is
produced.(IEC)
Overdrive. A term used to indicate use of greater than normal coil
current(applied voltage), and usually employed in obtaining fast operate time
or pulse response.
Overtravel armature dropout. The portion of the armature travel that
occurs between closure of the normally closed contact(s) and the fully released
static position of the armature.
Overtravel armature pickup. The portion of the armature travel occurring
between closure of the normally open contact(s) and the fully operated static
position of the armature.
Overtravel contact. See follow, contact.
Pickup, to pick up. A monostable relay picks up when it changes from the
unenergized condition to an energized condition.(IEC)
Pickup value, measured. As the current or voltage on an unoperated relay
is increased, the value at or below which all contacts function.
Pickup pulse. A short, high-level pulse applied to a relay; usually
employed to obtain fast-operate time.
Pickup value, specified. As the current or voltage on an unoperated
relay is increased, the value at or below which all contacts must function.
Pickup (or pull-in) time. See time, operate.
Pileup. An assembly of contact springs or combinations fastened one on
top of the other with insulation between them.
Pileup, contact. The total assembly of contacts in one stack on a
relay.
Pressure, contact. See force, contact.
Pneumatic bellows. Gas-filled bellows, sometimes used with plunger type
relays to obtain time delay.
Pole, double. A term applied to a contact arrangement to denote that it
includes two separate contact combinations, that is, two single-pole contact
assemblies.
Pole face. The part of the magnetic structure on the end of the core
nearest the armature.
Pole gap. See gap, armature.
Pole piece. The end of an electromagnet, sometimes separable from the
main section, and usually shaped so as to distribute the magnetic field in a
pattern best suited to the application.
Pole, single A term applied to a contact arrangement to denote that all
contacts in the arrangement connect in one position or another to a common
state.
Power dissipation PT The maximum average power dissipation at
a given load current.
Pretravel armature. The initial movement of the armature prior to
engagement with current.
Pull curve. The force-displacement characteristics of the actuating
system of the relay.
Pull-in time. See time, operate.
Pull-in (or pull-on)value measured See operating characteristics,
pickup value, measured.
Pull-in (or pull-on) value specified See operating characteristics,
pickup value, specified.
Pusher See buffer, armature.
