Capacitor Switching Contactors

Frako Capacitor Switching Contactors

Advanced Technology Contactors extend both Contactor and Capacitor life!

Hans von Mangoldt logoFRAKO Capacitor Switching Contactors are specifically designed for capacitor switching to achieve reliability and long life expectancy for your capacitor system.  Request for Quote

 FRAKO Contactors are available with or without pre-charge resistors:

Contactors with pre-charge resistors (K3-…K… type)

Contactor with Pre-charge Resistors

Contactor with Pre-charge Resistors

Modern capacitor systems use special contactors that are equipped with resistors to suppress the switching currents. The resistors are switched in series with the capacitor prior to the closing of the main contacts and removed from the circuit after energization, so as not to cause additional power losses. 


This feature is referred to as leading transition contact with pre-charge (or pre-insertion) resistor and offers these advantages:

  • Significant damping of inrush current
  • Suppression of voltage transients during switching
  • Protection for both capacitor and contactor
  • Extended capacitor and contactor life
  • May be used with and without series reactors
  • Increased system reliability




Contactors without pre-charge resistors (K3-…A… type)


Contactor without Pre-charge Resistors

Capacitors with series reactors (for tuning or detuning) have lower peak inrush current than systems that do not include reactors. For these applications, FRAKO offers contactors with special wear-resistant contact material which enables them to switch the reactor/capacitor network without the need for pre-charge resistors. These special contactors offer several advantages for capacitor switching applications that include series-connected reactors: Safe switching (ON and OFF) of reactor/capacitor steps

  • Improved voltage quality made possible through chatter-proof switching operations
  • Extended capacitor life
  • Extended contactor life (>100,000 switching operations)
  • Increased system reliability

Request for Quote

Call us 1-262-618-2403, Email or visit our Contact us page for Application Engineering or Quotes for Capacitor Switching Contactors.

Maximum Current (continuous):

K3-..K Contactors
(with resistors)
Amps in 50°C ambient0-1814-2814-3630-4830-7230-10850-11550-144
Amps in 60°C ambient0-1814-2814-3630-4830-7230-8750-10850-130
K3-..A Contactors
(w/o resistors)
Amps in 50°C ambient1828364832108115144
Amps in 60°C ambient182836487287108130


General Specification:

Maximum Voltage600 V600 V600 V600 V600 V600 V600 V600 V
Switching Time (msec)8-1610-2510-2512-2812-2812-2820-3520-35
Typical RK5 Fuse (A)5090125200250300300300
Typical T Fuse (A)70110150175175175300300
Power Loss  (Watts)3.5 W4.7 W5.3 W9.2 W10.9 W12.5 W9.3 W11.0 W
Terminal capacity Flexible (awg)2x(18-10)1x(14-4)1x(14-4)1x  (10-0)1x (18-3/0)  plus1x (8-4/0)
Terminal capacity Solid (awg)2x(18-10)1x(16-10)1x(16-10)1x(12-10)1x(12-10)1x(12-10)Use flexible wires
Coil Voltage range85% to 110% of rated coil voltage
Coil Terminals Flexible (awg)18-1218-1218-1218-1218-1218-1218-1218-12
Coil Terminals Solid (awg)14-1214-1214-1214-1214-1214-1214-1214-12
Weight (kg)0.340.620.621.
UL ApprovalFile # E 41502  for USA and Canada (UL-508)




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