Overview

The intelligent low-voltage power capacitor is an innovative reactive power compensation device that integrates compensation, communication, and multi-level fault protection into one compact unit—commonly referred to as the "intelligent capacitor."
The intelligent capacitor employs a high-speed chip to采集 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 capacitor itself utilizes advanced polypropylene metallized film technology with zinc-aluminum edge reinforcement, offering excellent self-healing capabilities, minimal capacitance degradation, superior shock resistance, and an exceptionally long service life. Additionally, the adoption of communication-based 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-on short circuit. Since it integrates 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 cuts down on 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—simply ensure the external wiring is correct, power it on, and it’s ready to run without requiring any settings.
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 separate incoming lines for weak and strong electricity, interference from primary circuits on 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-tripping 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. 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 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 ⑩-⑬ 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)
⑩-⑬: 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 degradation: ≤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 capacity expansion or component replacement straightforward.
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 specific 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. 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

Panel and Parameter Settings Guide

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 display, then cycle through the capacitor switching sequence by pressing the increment or decrement keys. 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 in sequence, and the corresponding indicator light illuminates accordingly.
When the power factor of reactive power in the grid shows leading, a delay is initiated. If this delay exceeds the preset time, 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 engage the capacitor banks one by one, while pressing the down key "↓" will forcibly disconnect any engaged capacitor banks. When in manual mode, all previously connected capacitors will be disconnected immediately.
(3) Over- and Under-Voltage as well as Harmonic Protection
When the grid voltage exceeds the overvoltage warning level, the digital display will show the actual overvoltage value, and the compensated capacitors will be quickly disconnected until the grid voltage drops below the preset overvoltage threshold. The capacitors can only be reconnected once the grid voltage falls below the preset value by 7V.
When the grid voltage drops below 20% of the rated voltage, the digital display shows the under-voltage value, and the system promptly disconnects the compensated capacitors until the grid voltage rises above the preset under-voltage threshold. The capacitors can only be reconnected once the grid voltage exceeds the preset threshold 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. Fuse is blown or power connection is open—check the fuse or the power cable connections.
b. The capacitor inside is damaged and needs to be replaced.
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 jumper 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 the load has a low power factor (cosφ) with significant lagging, resulting in a cosφ lower than 0.35.

The controller has entered protective mode.
b. Appropriately add a set of fixed compensating capacitors.
Fault 4: If cosφ falls below the set value, the controller will not engage.
Reason analysis: a. Low load, large capacitor capacity, and current reactive power below the threshold.
b. Reduce the 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 Supply 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 for cascaded communication networks between capacitors, as well as between cascaded secondary current transformers with through-core design.