CONTACTORS TYPE CN
CONTACTORS FOR CAPACITORS TYPE CN UP TO 3000V 50-250Hz

The switching of the usual three-phase power factor correction capacitors for motor or lines, is normally exploited by the standard type N contactors in the version with poles type V or S for voltage up to 1000V.
Special care must be taken for switching the capacitors (single-phase) used for power factor correction and current balancing of induction furnaces where high frequency of operation and remarkable presence of harmonics is expected.
The contactors CN are properly designed to withstand the increased thermal stresses due to harmonics exsting in the circuits feeding the capacitors, and to withstand for a great number of operations the highest overcurrents that may occur when connecting a capacitor.
According to the figured diagram (fig.1), for limiting the above mentioned transient current peaks, the contactor, wher provided in the plant, connects the capacitor through a proper limiting resistor, which, after a very short delay, is by-passed by the main pole that connects the capacitor directly to the line.
Moreover the contactor, when opening, can connect the capacitor across a discharge resistor by a proper contact.
The above metioned resistances, thet on request can be supplied with the contactor, must be carefully designed according to the performances of the contactor itself and in function of the number of operations per hour required.
For voltages up to 500V the contactors are fitted with poles without magnetic blowers or arc-chutes. For voltages over 500V the arcing poles are always of the magnetic blowed type with arc-chutes.
Moreover, for voltages over 1000V, two or more arcing poles connected in series are provided.

TYPE Rated Operational Current [A] Making current
[A] 		Max N° of oper./
hour
50Hz 100Hz 150Hz 250Hz
CN 85
70
65
60
42
3000
150
CN 125
100
90
85
60
3700
150
CN 190
150
135
125
95
4500
150
CN 270
200
180
170
135
8000
100
CN 350
250
225
210
175
9000
100
CN 550
400
360
340
275
10000
100
CN 650
460
410
390
325
13000
100
CN 800
560
500
480
400
16000
60
CN 1000
700
630
600
500
20000
60
CN 1250
900
800
750
650
30000
60

 

 

 

I = arcing pole
C = main pole
S = discharge resistance connecting contact

RI = limiting resistance
RS = discharge resistance

For reactive power higher than 0,5 KVAR, a discharge resistor must be always provided

 

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