Page 831 - Motor_protection_and_control_Manual_motor_starters_ contactors

Terms and technical definitions

Electrical durability – Opening time: Time interval between the coil
Number of on-load operating cycles that the contactor is able to carry de-energization and the instant the contacts separate on all the
out. It depends on the operational current, the operational voltage and poles.
the utilization category.
Rated control voltage Uc
Mechanical durability Control voltage value for which the control circuit is sized.
Number of no-current operating cycles that a contactor is able to carry
out. Rated operational voltage Ue
Voltage to which the contactor's utilization characteristics refer. In
Assessed failure rate three-phase it is the phase-to-phase voltage.
Defined according to IEC 60947-5-4. This rate is given in standard
industrial environments for the contactor relays and for the built-in Rated insulation voltage Ui
auxiliary contact of contactors.
Reference voltage for dielectric tests and creepage distances.
Load factor Rated impulse withstand voltage Uimp
Ratio of the on-load operating time to the total cycle time x 100.
Peak value of an impulse voltage, having a specified form and polarity,
which does not cause breakdown in specific test conditions.
Switching frequency
Number of switching cycles per hour. Shock withstand
Requirement for vehicles, crane drives, installations on board ships and
Plugging plug-in equipment. For the acceptable "g" values, the contacts must
Stopping or fast reversal in rotation direction of a motor by two supply not change position and the thermal overload relays must not trip.
leads being interchanged while the motor is running.
Resistance to vibrations
Inching Requirements for vehicles, boats and other means of transport. For
Energization of a motor's circuit repeatedly or for short periods with the the specified vibration amplitude and frequency values the device must
aim of obtaining small movements of the driven mechanism. remain able to operate.

Coil operating limits Mirror contacts
Expressed in multiples of the nominal control circuit voltage Uc for the Definitions of mirror contact acc. to IEC 60947-4-1, Annex F 2.1.
upper and lower limits. Normally closed auxiliary contact (N.C.) which cannot be in the closed
position simultaneously with the normally open (N.O.) main contact.
Mounting position Mechanically linked contact
Comply with the manufacturer's instructions. Restrictions are to be
taken into account for certain mounting positions. Definitions of mechanically linked elements acc. to IEC 60947-5-1,
Annex L.
Combination of "n" Make auxiliary contact element(s) and "m" Break
Rated breaking or making capacity auxiliary contact element(s) are designed in such a way that they can-
Root mean square (r.m.s.) value of the current that the contactor is not be in the closed position simultaneously.
able to break or make at a given voltage according to the conditions One control circuit device may have more than one group of mechani-
specified by standards and for a given utilization category. cally linked contact elements. 13

Intermittent duty
Duty during which the contactor is successively closed or open for
periods which are too short to enable the contactor to achieve thermal
balance.

Ambient temperature
Air temperature close to the contactor.

Time
– Time constant: Ratio of the inductance to the resistance
(L/R = mH/Ω = ms).
– Short-time withstand current: Current that the contactor is able to
withstand in closed position for a short time interval and in specified
conditions. 1SBC101625S0201 - Rev. C
– Closing time: Time interval between the coil energization and the
instant the contacts touch on all the poles.

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