Low Voltage Capacitor Contactor

Specifically crafted for safe operation in common distribution networks, the CJ36C Low Voltage Capacitor Contactor is a dedicated switching device for controlling low-voltage shunt capacitors. It is a preferred component within automatic compensation equipment used for power factor enhancement. This robust product is fully compatible with AC systems rated at 50Hz with a maximum working voltage of 380V, expertly managing the switching of capacitor banks up to 50kvar to optimize electrical efficiency. As an evolution based on the B-series AC contactor, the CJ36C Low Voltage Capacitor Contactor is a newer product in our lineup, available in five specifications to cater to different low-voltage application scales. Its structural design presents a key upgrade: the resistor switching circuit is mounted on both sides of the main power contacts and is complemented by an attached discharge device. This device automatically connects to the capacitors when they are taken off-line, ensuring any dangerous residual voltage is reduced to less than 50V within 30 seconds. This intrinsic feature of the product offers users tangible savings by eliminating the need for and expense of additional external discharge hardware. The main contacts maintain a logically designed configuration for secure and reliable individual load operation. To achieve dependable performance in typical low-voltage environments, this contactor must be installed and used under these standard conditions: a) Permissible ambient air temperature ranges from ≥-5°C to +40°C, with the 24-hour mean temperature not exceeding +35°C. b) The installation site altitude should not be higher than 2000m. c) Air relative humidity at the location must be ≤50% when the temperature is +40°C. Furthermore, the average minimum temperature of the wettest month is ≤+25°C, and that month's average maximum relative humidity is ≤90%. d) It is designed for pollution degree 3 settings. e) The installation category is III. f) It must be placed where significant shaking, impact, or vibration is absent. g) The mounting surface can have an inclination up to 5° relative to vertical.

The operational intelligence of this Low Voltage Capacitor Contactor is depicted in Figure 1. The circuit diagram above the dotted line illustrates the switching logic, with the capacitor bank shown below. Upon activation of the electromagnetic coil, the resistor switching circuit (early-make contacts with series resistors) closes first. Current flows through these resistors to pre-charge the capacitors, effectively suppressing the initial inrush current. The main contacts then close, taking over the current flow and short-circuiting the resistors. During deactivation, the sequence is protective: main contacts break first, followed by a delayed opening of the resistor circuit to mitigate switching overvoltage. Moreover, two normally-closed (break) contacts work in conjunction with the resistors to create a discharge circuit. When the contactor is engaged, this circuit is open; when released, it closes to safely discharge the capacitors. The CJ36C product features a two-path resistor switching arrangement. Given that the capacitors it controls are internally connected in a delta formation, this ensures that a current-limiting resistor is present in each phase circuit during the critical switching moment, providing balanced and thorough protection for your low-voltage capacitor assets.

Auxiliary contact configuration: The CJ36C-75 model can be equipped with 6 auxiliary contacts.

Two types of auxiliary contacts are available:

CA7-10 (normally open) and CA7-O1 (normally closed). Users can specify their requirements when ordering.

Note: 1. Because parallel capacitors operate under an overcurrent of 1.3ln for extended periods, and capacitors in power systems always operate at full load, these conditions are considered in the capacitor design. Therefore, the contactor and connectors for switching the capacitor must be able to withstand a continuous overcurrent of at least 1.3In (not considering the capacitor's allowable positive deviation of +15%). Therefore, it is recommended to use this type of contactor according to the parameters in parentheses.

2. In - Rated current of the capacitor.

Outline and Installation Dimensions

The CJ36C-75 type can be installed using M5 screws and anti-loosening washers, or using 35mm or 75mm mounting rails.