Capacitor Switch Contactor

Introducing the CJ36C Capacitor Switch Contactor (hereafter the contactor), a dedicated device developed for making and breaking low-voltage shunt capacitors. It is widely employed in automatic compensation reactive power compensation systems. This advanced product is suitable for AC power networks with a frequency of 50Hz and a rated operational voltage up to 380V, capable of switching capacitor loads up to 50kvar to effectively improve the system power factor. The CJ36C Capacitor Switch Contactor is a newly developed product derived from the B-series AC contactor platform, currently available in five specifications. Its structure differs slightly from previous models: the resistor switching circuit is positioned on both sides of the main circuit section and includes an attached discharge device. When capacitors are disconnected from the circuit, this discharge device automatically connects to them, enabling the residual voltage within the capacitors to drop below 50V within 30 seconds. This integrated feature allows users to eliminate external discharge devices, thereby reducing overall system costs. The main contacts maintain a rational design for reliable individual load operation. For optimal performance, the product must operate under these conditions: a) Ambient air temperature: upper limit +40°C, 24h average ≤+35°C, lower limit ≥-5°C. b) Altitude ≤2000m. c) Relative humidity at +40°C ≤50%; the average minimum temperature of the wettest month ≤+25°C, and that month's average max relative humidity ≤90%. d) Pollution degree: 3. e) Installation category: III. f) Must be installed where there is no significant shaking, impact, or vibration. g) Mounting surface inclination relative to vertical ≤5°.

The working principle is detailed in Figure 1. Above the dotted line is the capacitor switching schematic; below is the capacitor bank. The early-make contacts with series resistors form the resistor switching circuit. Upon coil energization, this circuit closes first, charging capacitors through the resistors to suppress inrush current. Main contacts then close, carrying the capacitive current and simultaneously short-circuiting the switching resistors. Upon contactor release, the main contacts open first, followed by a delayed opening of the resistor circuit to suppress switching overvoltage. Two normally-closed (NC) contacts and resistors form a discharge circuit. When the contactor pulls in, the resistors disconnect from the capacitors; upon release, they connect in parallel to discharge the capacitors. The CJ36C Capacitor Switch Contactor has only two resistor switching paths (see Fig. 1). As the capacitors are internally delta-connected, when the resistor circuit engages, each phase of the capacitor circuit has a resistor connected, ensuring balanced inrush suppression.

Auxiliary contact configuration: The CJ36C-25 contactor comes with one normally open (normally open) auxiliary contact. Auxiliary contacts can be configured at the top of the contactor; the CJ36C-25 can be configured with four auxiliary contacts.

Appearance and Installation Dimensions:

The contactor is easy to install. The CJ36C-25 model can be installed with M4 screws and lock washers, or with a 35mm mounting rail.