Himel Capacitor Switching Contactors


The capacitor switching contactors have resistors connected in series with the capacitors that are switched before the closing of the contacts and are promptly removed post the circuit is energised. Though, this seems a trivial affair, but it plays a pivotal role in significantly damping of inrush current and suppression of voltage transients during switching. This in turn aids in increasing the functional reliability of the electrical circuit. In a nutshell, the capacitor switching contactors are an extremely crucial switchgear of the circuit, which governs the flow of electrical power. These are installed in single or multi – step capacitor banks in commercial and residential spaces.

How does a Capacitor Switching Contactor operate?

Connections of capacitor banks directly to an electrical circuit would cause high transient currents, the peak value of which can rise to 100 – 150 times the ratings of the capacitor. These would lead to voltage oscillations that can be catastrophic to the components of the circuits. To counter the irregularities, resistors are switched in series with the capacitor banks. In the first setup, the resistors reduce the effect of peak and the inrush current. Post the closing of the main contacts, auxiliary contact ceases. The helps in avoiding voltage undulations and improves power quality besides increasing the capacitor life and reducing losses.

Himel HDC19s Capacitor Switching Contactors

 HDC19s is a range of contactors from Himel dedicated for switching of capacitors and is developed based on 3 series contactors, reducing the closing current impact. Salient features include the high current range cover from 25A to 170A. There are various auxiliary contact types that can be selected for numerous applications. Let us dive into the more in-depth details of the HDC19s Capacitor Switching Contactors from Himel

Selection Code

Primarily, understanding the selection codes of the capacitor switching contactors; to start with is the range name, HDC19s, which is followed by the numerical denoting the frame current varying from 25A to 175A. Next to the sequence, we have the list of auxiliary contacts based on the number of NO and NC contacts. Further to that, the next alphabet signifies the coil voltage for switching contactors. The last number 5/7 denotes the frequency of the AC, whether 50 Hz or 50/60Hz

Power and Current Ratings

Himel HDC19s comes with an operating voltage of 380/400V and insulation voltage of 690V. The rated current of controlled capacitor varies with the different frame current.

Mechanical & Electrical endurance

Himel contactor switching contactors are extremely robust and are tested for about 10,000 mechanical and electrical operations.

Working Conditions

The daily average temperature of operation is less than equal to 35degree C, with the ambient temperature from -5degree C to +40degree C. The atmospheric relative humidity does not exceed 50% when the highest ambient temperature is +40degree C. It is allowed to have a relative higher humidity under lower temperature, for instance up to 90% at +20degree C. The installations, however, should be in the absence of a significant shock and vibration point.