Overview

The intelligent low-voltage power capacitor is an innovative reactive power compensation device that integrates compensation, communication, and multi-fault protection into one compact unit—commonly referred to as the "smart 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 metallized 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 size is significantly reduced, allowing more high-capacity intelligent capacitors to be installed within the same capacitor cabinet. This also shortens installation time and makes future capacity expansions easier. Additionally, it can be applied to reactive power automatic compensation systems for centralized, local, and pole-mounted distribution lines.

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, network operation remains unaffected. 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 separate weak-current and strong-current incoming lines, interference from primary circuits to secondary signal lines is prevented, significantly enhancing the overall anti-interference performance of the device.
4. Preventing the Hazard of Reactive Power Backflow: A permanent fault-trip protection device is employed. Once a short circuit occurs in the smart capacitor, the system will automatically trip and disconnect from the grid, thereby preventing reactive power backflow that could harm the grid and ensuring 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 2 times the rated value, significantly reducing the impact on the power grid.
6. Fully equipped with 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 system 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 (Six-Circuit, Eight-Circuit)

Intelligent Integrated Power Capacitor Compensation Device
- □ / □ / 120 (10F + 10S + 20S) / LCD / □ 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨
① ② ③ ④ ⑤ ⑥-⑦ ⑧-⑩ ⑪-⑬ ⑩ ⑮
①: Enterprise Code
②: Product Code
③: Product Category: N4S (Molded Case) Series
④: Rated Voltage: 250V, 450V
⑤: Total capacity of this group is 60/120 kvar
⑥-⑦: Capacities of Groups 1 and 2: Split compensation, 10 + 20 kvar
(F: Partial Supplement, S: Shared Supplement)
⑧–⑩: Groups 3, 4, and 5—Total compensation: 10 + 10 + 10 kvar (F: individual compensation, S: collective compensation)
⑪-⑬: Groups 6, 7, and 8—Total compensation capacity: 20 + 20 + 20 kvar (F: individual compensation, S: collective compensation)
⑩ : LCD: Liquid Crystal Display
⑮: T: Temperature-controlled dry contact No: Without

Technical Specifications

1. Altitude: ≤2000m;
2. Ambient temperature: -30～+55°C;
3. Relative humidity: ≤80% (at 25°C);
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;
8. Control Method: RS485 communication, RJ45 interface;
9. Rated Capacity: Hybrid compensation ≤120 (10F + 20F + 10S + 10S + 10S + 20S + 20S + 20S) kVAR;
10. Power Consumption: ≤6W;
11. Product Application Scope
Agricultural grid construction, residential and building infrastructure development, and industrial applications using non-harmonic devices—all of which operate within the national standard limits for harmonic content (in facilities where total harmonics remain below 10%).

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
It primarily serves 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 de-energization. This prevents common issues during switching, such as contact sticking and operational overvoltage. As a result, not only is the capacitor's lifespan extended, but the impact and pollution caused by inrush currents on the power grid are also significantly reduced.
5. Smart Networking
The smart capacitor operates as a self-contained system; if an individual smart capacitor fails, it automatically shuts down without affecting the operation of the others.

Smart Capacitor Specifications and Installation Dimensions

Installation and overall dimensions (height for six-unit combination: 329, height for eight-unit combination: 418)

Panel and Parameter Setting Instructions

In automatic mode: The current display shows the identifier; press the ↑ ↓ keys to switch between function displays. Identifier meanings:

Button Instructions
Press the menu key to cycle through the function parameters; press the ↑ key to increase the parameter value under the selected function, and press the ↓ key to decrease it.

Manual, manual switching

Use the function keys to navigate to the left-hand diagram, then cycle through the capacitor switching sequence by pressing the increment or decrement buttons. The current power factor of the grid is displayed in real time (on the manual interface, press the ↑ key to connect capacitors, and the ↓ key to disconnect them).

Operating Method

(1) Automatic Operation
Connect the power supply and sample the current. When the reactive power in the grid exceeds the switching threshold, a delay is initiated. If the delay time is surpassed, the capacitor banks are automatically switched on one by one, and the corresponding indicator lights illuminate sequentially.
When the power factor of reactive power in the grid shows leading, a delay is initiated. Once this delay time is exceeded, the system automatically disconnects the previously connected capacitor banks one by one, causing the corresponding output indicator lights to turn off sequentially.
(2) Manual Operation
Set the "Menu" key to manual operation mode. Pressing the up key "↑" will forcibly connect capacitor banks one by one, while pressing the down key "↓" will forcibly disconnect the already connected capacitor banks. When in manual mode, previously connected capacitors remain active.

All containers have been removed.
(3) Over- and Under-Voltage and Harmonic Protection
When the grid voltage exceeds the overvoltage warning level, the digital display shows the actual overvoltage value and promptly disconnects the compensated capacitors until the grid voltage drops below the preset overvoltage threshold. The capacitors can only be reconnected once the grid voltage falls below the preset 7V level.
When the grid voltage drops below 20% of the rated voltage, the digital display shows the undervoltage value and promptly disconnects the previously compensated capacitors until the grid voltage rises above the preset undervoltage threshold. The capacitors can only be reconnected once the grid voltage exceeds the undervoltage preset by at least 7V.
(4) When grid harmonics exceed the preset harmonic protection threshold, the digital display shows the total grid harmonics and promptly disconnects the compensated capacitors.

Common Fault Handling

Fault 1: No display after power-on.
Cause Analysis: a. The fuse is blown or the power connection is open—check the fuse or the power cable connections.
b. The capacitor must be replaced due to internal damage.
Fault 2: Analysis of the cause for no current after power-on.
Cause Analysis: a. The power signal line is open-circuited, or the CT shorting wire has not been disconnected.
b. The grid load is low, and the CT secondary-side current is less than 100mA.
Fault 3: Displays C0.00 after power-on.
Cause Analysis: a. The transformer has high losses or a low load power factor (cosφ) with significant lagging, causing the controller to enter protection mode when cosφ drops below 0.35.
b. Appropriately add a set of fixed compensation capacitors.
Fault 4: If cosφ is lower than the set value, the controller will not engage.
Reasons for analysis: a. Low load, large capacitor capacity, and current reactive power below the threshold.
b. Reduce capacity.
Fault 5: cosφ value displayed as negative
Cause Analysis: a. The phase sequence of the voltage or current signal lines is incorrect; check according to the wiring diagram and reconnect properly.
b. If internal damage occurs and the output becomes abnormal, replacement is required.

Wiring

1. Power Cable Wiring
The power wiring must be connected in the sequence of Ua, Ub, Uc, Un, and the grounding incoming line.

2. Signal Connection
RJ45 is the port used for cascaded communication between capacitors, as well as between cascaded secondary current transformers.