Page 833 - Motor_protection_and_control_Manual_motor_starters_ contactors

Standards and utilization categories

Utilization categories (cont.)

DC power circuit switching
Arc suppression is more difficult in direct current than in alternating current. Higher the time constant and voltage, heavier the breaking conditions:
consequently several poles have to be connected in series.

AC high current circuit switching
Possibility of increasing performances by connecting poles in parallel.

Circuit switching during temporary and intermittent duty
In these cases higher operational currents are acceptable.

Influence of the length of the conductors used in the contactor control circuit
According to the operational voltages, the cross-sectional areas, the coil consumption and the control layout, difficulties due to line resistances
and capacitances may appear during contactor closing and opening orders.

Making and breaking conditions for utilization categories

Utilization category Durability test conditions Occasional operation
Making and breaking capacities - 50 operating cycles
Making conditions Breaking conditions Making conditions Breaking conditions
I/Ie U/Ue Cos. ϕ I/Ie U/Ue Cos. ϕ Ic/Ie Ur/Ue Cos. ϕ Ic/Ie Ur/Ue Cos. ϕ
or or or or
L/R (ms) L/R (ms) L/R (ms) L/R (ms)
Contactors for AC circuit switching
AC-1 1 1 0.95 1 1 0.95 1.5 1.05 0.8 1.5 1.05 0.8
AC-2 2.5 1 0.65 2.5 1 0.65 4 1.05 0.65 4 1.05 0.65
AC-3 Ie < 17 A 6 1 0.65 1 0.17 0.65 10 1.05 0.45 8 1.05 0.45
17 < Ie < 100 A 6 1 0.35 1 0.17 0.35 10 1.05 0.45 8 1.05 0.45
Ie > 100 A 6 1 0.35 1 0.17 0.35 10 1.05 0.35 8 1.05 0.35
AC-4 Ie < 17 A 6 1 0.65 6 1 0.65 12 1.05 0.45 10 1.05 0.45
17 < Ie < 100 A 6 1 0.35 6 1 0.35 12 1.05 0.45 10 1.05 0.45
Ie > 100 A 6 1 0.35 6 1 0.35 12 1.05 0.35 10 1.05 0.35
Contactors for DC circuit switching
DC-1 1 1 1 1 1 1 1.5 1.05 1 1.5 1.05 1
DC-3 2.5 1 2 2.5 1 2 4 1.05 2.5 4 1.05 2.5
DC-5 2.5 1 7.5 2.5 1 7.5 4 1.05 15 4 1.05 15

Contactor relays for AC circuit switching
AC-14 (≤ 72 VA) – – – – – – 6 1.1 0.7 6 1.1 0.7
AC-15 (> 72 VA) 10 1 0.7 1 1 0.4 10 1.1 0.3 10 1.1 0.3
13

Contactor relays for AC circuit switching
Utilization category Standard operation Occasional operation
Making and breaking capacities - 50 operating cycles
Making conditions Breaking conditions Making conditions Breaking conditions
I/Ie U/Ue T 0.95 I/Ie U/Ue T 0.95 Ic/Ie Ur/Ue T 0.95 Ic/Ie Ur/Ue T 0.95
DC-13 1 1 6 P(1) 1 1 6 P(1) 1.1 1.1 6 P(1) 1.1 1.1 6 P(1)
DC-14 – – – – – – 10 1.1 15 ms 10 1.1 15 ms
(1) The value "6 x P" is the result of an empirical relation which is estimated to represent most DC magnetic loads up to the highest limit of P = 50 W (6 x P = 300 ms). It is accepted
that loads having drawn energy above 50 W are made up of weaker loads in parallel. As a consequence, the 300 ms value must form the highest limit whatever the value of the
power drawn.
Key:
U (I) = applied voltage (current) Ic = making and breaking current expressed in DC or in AC like
Ur = recovery voltage the r.m.s. value of the symmetrical components
L/R = test circuit time constant T 0.95 = time required to reach 95 % of the current in steady-state 1SBC101626S0201 - Rev. A
Ue (Ie) = rated operational voltage (current) conditions, expressed in milliseconds

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