Page 424 - ABB_Motor _Protection_and_Control_catalogue_20221216

3/348 ABB MOTOR PROTECTION AND CONTROL

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Surge suppressors for contactor coils

The operation of inductive circuits causes overvoltages, in particular on opening of the contactor coil.
(V)
1000 The electromagnetic energy stored in the coil during contactor closing is restored on opening in
03
T (µs) the form of surges, the slope and amplitude of which may rise to several kilovolts. A number of
0 100 drawbacks are observed ranging from interference on the electronic devices to breakdown of in-
1000
sulators and even destruction of certain sensitive components.
0 100 The graph opposite reproduces the oscillogram showing voltage discharges at the terminals of a
42 V / 50 Hz coil without peak clipping. The coil was switched by 8 series-connected poles of a
A 884D contactor relay.
Following a burst of discharges with a very steep slope a damped oscillation emerges with a peak
value of 3500 V.
Overvoltage Factor
The overvoltage factor k is defined as the ratio of the maximum overvoltage peak value Ûs to the
peak value Ûc of the coil rated control voltage Uc:
k = Ûs max. in DC: k = Ûs max. or in AC: k =
Ûs max.

1SBC574001F0301 Ûc Uc Uc√2
3500
42 √2
RV5/50 For example the following is obtained for the above graph: k = ≈ 60
To reduce the harmful effects of these overvoltages, ABB has developed a range of surge suppres-
sors designed to reduce the k factor defined above and to limit or even completely eliminate the
high pre-damping voltage frequencies.
Each case is different, but the technical data tolerances and the generous sizing of parts have en-
abled us to reduce the number of variants.
We have chosen the following solutions: transil diodes, varistors and RC blocks.
Note: A varistor is a resistor whose value decreases to a very large extent when a certain voltage is
1SBC573891F0301 applied at its terminals.
For contactors
Rated control circuit
voltage Type Order code Pkg Weight
qty
RC5-1/50
Uc (1 pce)
V AC DC kg
UA, UA..RA 24...50 ● ● RV5/50 1SBN050010R1000 2 0.015
GA75, GAE75 50...133 ● ● RV5/133 1SBN050010R1001 2 0.015
110...250 ● ● RV5/250 1SBN050010R1002 2 0.015
250...440 ● ● RV5/440 1SBN050010R1003 2 0.015
UA16...UA30, UA16RA...UA30RA 24...50 ● – RC5-1/50 1SBN050100R1000 2 0.012
50...133 ● – RC5-1/133 1SBN050100R1001 2 0.012
110...250 ● – RC5-1/250 1SBN050100R1002 2 0.012
250...440 ● – RC5-1/440 1SBN050100R1003 2 0.012
UA50...UA110, UA50RA...UA110RA 24...50 ● – RC5-2/50 1SBN050200R1000 2 0.015
GA75 50...133 ● – RC5-2/133 1SBN050200R1001 2 0.015
110...250 ● – RC5-2/250 1SBN050200R1002 2 0.015
250...440 ● – RC5-2/440 1SBN050200R1003 2 0.015
GAE75 12...32 – ● RT5/32 1SBN050020R1000 2 0.015
25...65 – ● RT5/65 1SBN050020R1001 2 0.015
50...90 – ● RT5/90 1SBN050020R1002 2 0.015
77...150 – ● RT5/150 1SBN050020R1003 2 0.015
150...264 – ● RT5/264 1SBN050020R1004 2 0.015