Page 230 - Contactors_Catalogue

4/30 ABB MOTOR CONTROL AND PROTECTION FOR ROLLING STOCK APPLICATIONS

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AF09(Z)B ... AF370B 3-pole contactors
Electrical durability and utilization categories

General Electrical durability forecast and contactor selection for
Utilization categories determine the current making and mixed duty motor control: AC-3 (Ic = Ie) type switching off
breaking conditions relating to the characteristics of the while "motor running" and, occasionally, AC-4 (Ic = 6 x Ie)
loads to be controlled by the contactors. International type switching off while "motor accelerating"
standard IEC 60947-4-1 and European standard EN 60947-4-1
are the standards to be referred to. Characteristics Load to be controlled
If Ic is the current to be broken by the contactor and Ie the Operational voltage Ue
rated operational current normally drawn by the load, then: Current normally drawn Ie (Ue / Ie / kW relation for motors, see
• Categories AC-1 and AC-3 Ic = Ie while "motor running" "Motor rated operational powers and
currents")
• Category AC-2 Ic = 2.5 x Ie Utilization category AC-1, AC-2, AC-3 or AC-4
• Category AC-4 Ic = 6 x Ie Breaking current for AC-3 Ic = Ie
Generally speaking Ic = m x Ie where m is a multiple of the Breaking current for AC-4 Ic = 6 x Ie
load operational current. while "motor accelerating"
Percentage of AC-4 K (on the basis of the total number of
operating cycles operating cycles)
04
On next pages, the curves corresponding to categories AC-1, • Define the total number of operating cycles N required.
AC-3 and AC-4 represent the electrical durability variation of • Note the smallest contactor rating compatible for AC-3
standard contactors in relation to the breaking current Ic. (Ue / Ie) on Main pole utilization characteristic table
Electrical durability is expressed in millions of operating (see “Technical data”).
cycles.
• For the selected contactor make a note of the following in
relation to the voltage using diagram AC-3 in next pages:
Curve utilization mode - The number of operating cycles A for Ic = Ie (AC-3)
Electrical durability forecast and contactor selection for - The number of operating cycles B for Ic = 6 x Ie (AC-4)
categories AC-1, AC-2, AC-3 or AC-4 • Calculate the estimated number of cycles N’ (N’ is always
below A)
Characteristics Load to be controlled
Operational voltage Ue N'= A
Current normally drawn Ie (Ue / Ie / kW relation for motors, see 1 + 0.01 K (A/B - 1)
"Motor rated operational powers and
currents") • If N' is too low in relation to the target N, calculate the
Utilization category AC-1, AC-2, AC-3 or AC-4 estimated number of cycles for a higher contactor rating.
Breaking current Ic = Ie for AC-1 and for AC-3 ; Ic = 2.5 x Ie for
AC-2 ; Ic = 6 x Ie for AC-4
Case of uninterrupted duty
• Define the number of operating cycles N required. For uninterrupted duty, some verifications of preventing
• On the diagram corresponding to the operational maintenance are necessary to check the functionality of
category, select the contactor with the curve immediately the concerned product (consult us).
above the intersection point (Ic ; N). The combinated effect of environmental conditions and
the proper temperature of the product may require some
disposals. As a matter of fact, for this duty, the use duration
prevails over the number of operating cycles.

1SBC101837S0201 - rev. A