Overview

The reactive power compensation intelligent low-voltage power capacitor is a novel device that integrates compensation, communication, and multi-level fault protection into one compact unit. It is commonly referred to as the "Intelligent Capacitor."
The intelligent capacitor control system uses a high-speed chip to acquire AC current signals, paired with a zero-crossing switching device that minimizes stress on the capacitor, thereby extending its lifespan and reducing the impact of inrush currents on the power grid. The capacitors themselves feature advanced polypropylene metalized film technology with thickened zinc-aluminum edges, offering excellent self-healing capabilities, minimal capacitance degradation, superior shock resistance, and an exceptionally long service life. Additionally, the integration of communication-enabled multi-unit control significantly enhances the overall reliability of the system.
The intelligent capacitor features multiple protection functions, including overcurrent, power failure, harmonic, overtemperature, pressure, and automatic trip in case of short circuits. By integrating protection, switching, and compensation into a single unit, its compact design significantly reduces the overall footprint—allowing more high-capacity intelligent capacitors to be installed within the same capacitor cabinet. This not only streamlines installation time but also makes future capacity expansions easier and more convenient. Additionally, it is ideally suited for reactive power automatic compensation in centralized, local, and pole-mounted distribution systems.

Functional Features

1. Easy operation: The human-machine interface is simple—just ensure the external wiring is correct, power it on, and it’s ready to run immediately, requiring no setup whatsoever.
2. Simple multi-unit series connection: Whether the smart capacitor is disconnected or connected, it does not affect network operation. As long as the smart capacitor is connected, it will automatically join the compensation sequence—no additional conditions required. This significantly simplifies the process of connecting multiple smart capacitors in series.
3. Strong anti-interference capability: By adopting a separate incoming power supply for weak and strong currents, interference from primary lines on secondary signal lines is prevented, significantly enhancing the overall anti-interference performance of the device.
4. Preventing Reverse Reactive Power Hazards: A permanent fault-trip protection device is employed, ensuring that the smart capacitor automatically trips and disconnects from the grid in the event of a short circuit. This prevents reverse reactive power hazards caused by faults, thereby maintaining the stable operation of the reactive power compensation system.
5. Small inrush current during switching: Utilizing advanced zero-crossing switching technology, the inrush current during energization is limited to within 2Ie times, significantly reducing the impact on the power grid.
6. Comprehensive protection features: In addition to a permanent fault trip protection device, it also includes overcurrent protection, power-loss protection, and an explosion-proof pressure protection device built into the capacitor.
7. Long-lasting capacitor: Utilizing polypropylene metalized film with thickened zinc-aluminum edges, this capacitor boasts excellent self-healing capabilities, minimal capacitance degradation, strong shock resistance, and an extended service life.

8. Convenient Maintenance: The control unit is designed as a separate component from the capacitors, making maintenance easy. Secondary signals between the capacitors are directly cascaded using the included network cables.

Model Description

CHKC-N3, N3S Series
Intelligent Integrated Power Capacitor Compensation Device
CH KC - □ / □ / 60 (20F + 10S + 10S + 20S) / LCD
丨 丨 丨 丨 丨 丨 丨 丨 丨 丨
① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ⑩
①: Enterprise Code
②: Product Code
③: Product Categories: N3 (Miniature Circuit Breaker), N3S (Molded Case)
④: Rated Voltage: 250V, 450V
⑤: Total Capacity of This Group
⑥: First group capacity: Step-up 20kvar
(F: Partial Supplement, S: Shared Supplement)
⑦: Second group capacity: Total compensation of 10 kvar
(F: Partial Supplement, S: Shared Supplement)
⑧: Group 3 Capacity: Total Compensation of 10 kvar
(F: Partial Supplement, S: Shared Supplement)
⑨: Group 4 Capacity: Total Compensation of 20 kVAR
(F: Partial Supplement, S: Shared Supplement)
⑩: LCD: Liquid Crystal Display, LED: Digital Display

Technical Specifications

1. Altitude: ≤2000m;
2. Ambient temperature: -45 to +55°C;
3. Relative humidity: ≤80% (at 25℃);
4. Environmental requirements: No harmful gases, no conductive or explosive dust, and no severe mechanical vibrations;
5. Rated voltage: 380V ±20% 50Hz ±5%;
6. Capacitor capacitance decay: ≤1% per year;
7. Switch lifespan: 300,000 cycles;
 

How it works

The intelligent capacitor consists of a miniature circuit breaker, AC signal sampling circuit, CPU control, zero-crossing switching device, communication module, and self-healing power capacitors. It features standardized, modular design with a building-block installation approach, resulting in minimal heat generation and making it easy to expand capacity or replace components.
1. Miniature circuit breaker
Primarily functions as a power switch and provides short-circuit protection.
2. AC Signal Sampling Circuit
Use a precision current transformer to convert the capacitor's current into a value with a fixed ratio, providing it to the CPU for computation.
3. CPU Control
Its primary functions are measurement, switching control, communication, and fault handling. It measures and monitors the current flowing through capacitors, and when abnormal currents are detected, it either disconnects or blocks the capacitor from being switched in.
4. Zero-Crossing Switching Device
The smart capacitor is equipped with a zero-crossing switching device, which ensures smooth inrush-free energization and arc-free disconnection, preventing common issues such as contact sticking and operational overvoltage during switching. This not only extends the lifespan of the capacitor but also minimizes the impact and pollution caused by inrush currents on the power grid.
5. Self-healing Power Capacitors
The power capacitors utilize a polypropylene metallized film with zinc-aluminum edge-thickening technology, offering excellent self-healing capabilities, minimal capacitance degradation, strong shock resistance, long service life, and an integrated pressure protection device.

6. Protection Function
Smart capacitors not only offer compensation, zero-crossing switching, and communication functions, but more importantly, they come equipped with comprehensive built-in protection features. Typically, conventional power capacitors continue to operate regardless of harsh ambient temperatures or severe harmonic distortions. As a result, 80% of capacitor failures aren’t due to inherent quality issues—but rather external operating conditions. Even when additional protective devices are installed externally, these systems often remain in a reactive, rather than proactive, state of safeguarding. In contrast, smart capacitors integrate multiple protection mechanisms, such as overcurrent, undervoltage, pressure monitoring, and short-circuit tripping, into a single, robust unit. This ensures that the capacitor maintains an active, protective mode under all operating conditions, significantly reducing the likelihood of failure and extending its lifespan.
(1) Overcurrent Protection
Once the capacitor is put into operation, its current is continuously monitored. If the current exceeds 1.4 times the rated current, the capacitor is quickly disconnected from the circuit.
(2) Power-loss protection
When the power grid experiences a blackout, quickly disconnect the online capacitors to prevent surges that could strain the grid upon reconnection.
(3) Pressure Protection
Pressure protection primarily prevents capacitors from exploding during operation. When a large-area breakdown occurs inside the capacitor, it generates significant heat and gas, causing an instantaneous increase in internal pressure. If this pressure surge far exceeds the capacitor’s structural pressure rating, an explosion can occur. Since overcurrent and temperature protection mechanisms often have delayed response times, a pressure-based explosion-proof device is installed inside the capacitor. This device features two-phase voltages that pass through a fusible link within the explosion-proof assembly before connecting to the capacitor’s internal components. In the event of a widespread breakdown, the internal pressure rises sharply, leading to visible deformation of the capacitor’s outer casing—commonly referred to as "bulging." At this point, the fusible link in the explosion-proof device instantly breaks, immediately cutting off the power supply and halting the buildup of gaseous energy, thereby preventing a potential capacitor explosion.

Smart Capacitor Specifications and Installation Dimensions

1. Installation and Overall Dimensions

Compensation Capacity Grouping
Compensation capacity consisting of 120 kvar

Compensation capacity consisting of 60 kvar

Note: Smart capacitors of different capacities have consistent width and depth, with variations only in height.

Wiring

1. Power Cable Wiring
The power supply must be properly wired in the sequence of Ua, Ub, Uc, Un, and the grounded incoming line.

2. Signal Wiring
Attention: The capacitor status indicator outputs at terminals A1, A2, B1, B2, C1, and C2 are high-voltage terminals and must not be short-circuited with other terminals. A＋ and B－ are the terminal communication interfaces.

First-time Usage Tips

1. Panel Display

After the capacitor is powered on, it enters standby mode. When it gains host priority, it switches to host mode; if it doesn’t gain priority, it moves into slave mode. The host automatically receives data about the capacitor’s capacity, type, and other specifications. While in host mode, the host indicator light stays steadily on; when in slave mode, the light turns off. In all other states, the host indicator light flashes.

2. Key operation:
Press the SET button, and the system will switch between automatic, manual, and parameter setting modes.

2.1 Automatic Mode
Shared-supply host status:

Co-supply slave device status:

Split-supply host status:

Split-supply slave mode:

(1) When this capacitor is used as the main unit: In automatic mode, press the up or down buttons to switch between displaying power factor, voltage, current of connected equipment, reactive power, harmonics, and equipment ID number.
(2) When this capacitor operates as a slave device: In automatic mode, press the Up or Down key to switch the display to show: Device Number.
(3) On the power factor display screen, simultaneously press the up and down keys to enter simulation mode. In this mode, when you issue commands to switch capacitors in or out, the corresponding capacitor status indicator lights will illuminate—but no actual capacitor switching will occur. To exit simulation mode, simply press the up and down keys again simultaneously.

2.2 Manual Mode: Shared Replenishment Type:

Split-replenishment type:

(1) The manual mode is intended solely for testing the intelligent capacitor switching function. After activation, you can determine whether the capacitor is functioning properly by observing the capacitor current.
(2) In manual mode, press the up key to engage the capacitor, and press the down key to disengage it.
(3) In manual mode, the master unit can manually control the slave unit to switch in capacitors.
(4) When switching from automatic to manual mode, all capacitors already connected in the network will be disconnected. LED lights:
(1) Automatic Compensation: C1 represents the first capacitor switching state; C2 represents the second capacitor switching state. When a capacitor is switched in, the corresponding LED light turns on; when it’s switched out, the corresponding LED light turns off.
(2) Separate Compensation + Common Compensation: CA represents the switching status of the capacitor in phase A; CB represents the switching status of the capacitor in phase B; CC represents the switching status of the capacitor in phase C; △ indicates the switching status of the common compensation capacitor. When a capacitor is switched in, the corresponding LED light turns on; when it is switched out, the corresponding LED light turns off.

2.3 Parameter Settings:

Parameter Setting Status

Use the up and down keys on the settings screen to modify parameters. After finishing the parameter adjustments, press the menu button as needed until you reach the Auto Screen mode, at which point the parameters will be saved automatically.

Mode Guide

1. Capacitor power-up and network initialization for the first time:

1.1 When the capacitor is powered on simultaneously, the LCD screen displays "L--000," and the host light flashes, indicating that the device is in networking mode.

1.2 The LCD screen displays a power factor of A-phase CA-1.00. When the host light stops flashing and remains steadily lit, it indicates this unit is the master device. Conversely, if the host light stops flashing and turns off entirely, it means this unit is the slave device.
 

2. Manual Execution
2.1 After the network setup is complete, first set the capacitor parameters, then manually switch the capacitors on and off.
2.2 When the host is in simulation debugging mode, the main and auxiliary capacitor indicator lights will automatically flash, indicating that the system is currently in simulation debugging mode. In this state, when capacitors are manually switched in, only the indicator lights will change—no actual capacitors will be connected.
(Automatically, pressing the ↑ and ↓ keys simultaneously causes the lights to flash; currently, the system is in simulation mode. Pressing both up and down keys again will stop the flashing and exit simulation mode.)

3. Parameter Settings

On any screen of the settings interface, pressing the ↑ or ↓ keys—or holding down the ↑ or ↓ keys—will allow you to modify parameters. Once you’ve finished adjusting the parameters, press the Menu key to cycle out of the setting mode, returning to the automatic mode where the adjusted parameters are automatically saved.

Data Cleanup:
1. Clear network data: Press and hold the "↓" button while powering on the capacitor for 3 seconds.
2. Clear Input Cutout: Press the "↑" key while the capacitor is powered on, and hold for 3 seconds.

Capacitor Wiring Diagram

Wiring Diagram for Common Compensation (External Controller)

Hybrid Compensation (External Controller) Wiring Diagram

Combined Compensation (Built-in Controller) Wiring Diagram

Hybrid (Built-in Controller) Compensation Wiring Diagram