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Leon Zhang sales consultant
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Email: zxl635973785@gmail.com
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Phone/WhatsApp: +86 13655813266
87V Capacitor Differential Voltage Protection | Voltage Unbalance Protection for Capacitor Banks
Protection Functions
Three-stage overcurrent protection
Capacitor differential voltage protection
Zero-sequence overvoltage protection
Overvoltage protection with no-current blocking option
Undervoltage protection with current blocking option
Phase-to-ground overvoltage protection with no-current blocking, judged by phase voltage
Phase-to-ground undervoltage protection with current blocking, judged by phase voltage
Communication Mode:Optional: RS-485, CAN bus, Ethernet, IEC 60870-5-103 ,IEC61850
In-house Factory & Technical Team, OEM ODM Custom Electrical Equipment
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Description
Overview of Capacitor Differential Voltage Protection
- The ASC-447H Digital Capacitor Differential Voltage Protection Unit applies to medium and low voltage shunt capacitor banks.
Protection Functions
- Three-stage overcurrent protection
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Capacitor differential voltage protection
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Zero-sequence overvoltage protection
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Overvoltage protection with no-current blocking option
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Undervoltage protection with current blocking option
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Phase-to-ground overvoltage protection with no-current blocking, judged by phase voltage
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Phase-to-ground undervoltage protection with current blocking, judged by phase voltage
Communication Functions
- Three communication modes available: RS-485, CANBUS and Ethernet. Please specify when placing orders.
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Upload real-time data including measurement data, fault recording data, fault and alarm signals, protection settings, configuration and parameters. Remote online setting modification and protection switching are supported.
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Receive upper commands for remote control, time synchronization, setting adjustment and data read-write.
Control Cabinet Functions
- Built-in anti-tripping control circuit
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Adaptive closing and tripping current
Self-diagnosis Functions
- Automatic fault detection of RAM, ROM, A/D module and power loss
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Automatic verification of settings, configuration and parameters
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Event Record & Fault Recording
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Record protection trips and device abnormalities
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Log protection type, operating time and operating parameters during trips
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Record trip time, protection type and effective values before and after faults
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Waveform storage: 2 cycles before fault and 4 cycles after fault per channel
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48 groups of SOE records and 16 groups of fault reports can be retained after power loss
Monitoring Functions
- Measure analog quantities such as current, voltage and frequency
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Collect status signals of circuit breaker, energy storage, isolating switch and local/remote mode
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Circuit breaker closing and tripping control
Display Functions
- Chinese LCD screen, status indicators and operation keypad equipped. Support real-time monitoring, online setting modification and protection switching. Fault indicators can be reset locally or remotely.
Setting List of Capacitor Bank Unbalance Voltage Protection（59NU/59N）
| No. | Display Name | Range | Step | Remark |
|---|---|---|---|---|
| 1 | Stage 1 Protection Setting | |||
| 1.1 | Stage 1 Protection Switch | 1/0 | 1: Enable, 0: Disable Stage 1 Overcurrent Protection | |
| 1.2 | Stage 1 Time Delay | 0～120.00s | 0.01s | |
| 1.3 | Stage 1 Setting Value | 0.40～99.99A
0.10～20.00A |
0.01A | Rated Current In=5A
Rated Current In=1A |
| 2 | Stage 2 Protection Setting | |||
| 2.1 | Stage 2 Protection Switch | 1/0 | 1: Enable, 0: Disable Stage 2 Overcurrent Protection | |
| 2.2 | Stage 2 Time Delay | 0～120.00s | 0.01s | |
| 2.3 | Stage 2 Setting Value | 0.40～99.99A
0.10～20.00A |
0.01A | In=5A
In=1A |
| 3 | Stage 3 Protection Setting | |||
| 3.1 | Stage 3 Protection Switch | 1/0 | 1: Enable, 0: Disable Stage 3 Overcurrent Protection | |
| 3.2 | Stage 3 Time Delay | 0～120.00s | 0.01s | |
| 3.3 | Stage 3 Setting Value | 0.40～99.99A
0.10～20.00A |
0.01A | In=5A
In=1A |
| 4 | Overvoltage Protection Setting | |||
| 4.1 | Overvoltage Protection Switch | 1/0 | 1: Enable, 0: Disable Overvoltage Protection | |
| 4.2 | Overvoltage Time Delay | 0～120.00s | 0.01s | |
| 4.3 | Overvoltage Setting Value | 5～120.00V | 0.01V | |
| 5 | Undervoltage Protection Setting | |||
| 5.1 | Undervoltage Protection Switch | 1/0 | 1: Enable, 0: Disable Undervoltage Protection | |
| 5.2 | Undervoltage Time Delay | 0～120.00s | 0.01s | |
| 5.3 | Undervoltage Setting Value | 5～100.00V | 0.01V | |
| 6 | Differential Voltage Protection Setting | |||
| 6.1 | Differential Voltage Protection Switch | 1/0 | 1: Enable, 0: Disable Differential Voltage Protection | |
| 6.2 | Differential Voltage Time Delay | 0～120.00s | 0.01s | |
| 6.3 | Differential Voltage Setting Value | 0.5～25V | 0.01V | |
| 7 | Zero-sequence Overvoltage Setting | |||
| 7.1 | Zero-sequence Overvoltage Protection Switch | 1/0 | 1: Enable, 0: Disable Zero-sequence Voltage Protection | |
| 7.2 | Zero Voltage Time Delay | 0～120.00s | 0.01s | |
| 7.3 | Zero Voltage Setting Value | 5～120.00V | 0.01V | |
| 8 | Phase-to-ground Undervoltage Setting | |||
| 8.1 | Phase-to-ground Undervoltage Switch | 1/0 | 1: Enable, 0: Disable Phase-to-ground Undervoltage Protection | |
| 8.2 | Undervoltage Time Delay | 0～120.00s | 0.01s | |
| 8.3 | Undervoltage Setting Value | 5～70.00V | 0.01V | |
| 9 | Phase-to-ground Overvoltage Setting | |||
| 9.1 | Phase-to-ground Overvoltage Switch | 1/0 | 1: Enable, 0: Disable Phase-to-ground Overvoltage Protection | |
| 9.2 | Overvoltage Time Delay | 0～120.00s | 0.01s | |
| 9.3 | Overvoltage Setting Value | 5～70.00V | 0.01V | |
| 10 | General Setting | |||
| 10.1 | Bus PT Broken Line Detection | 1/0 | 1: Enable, 0: Disable | |
| 10.2 | Control Circuit Broken Line Detection | 1/0 | 1: Enable, 0: Disable | |
| 10.3 | Current Blocking Over & Under Voltage | 1/0 | 1: Enable, 0: Disable | |
| 10.4 | 1A Rated Current Selection | 0.1～99.99A | 0.01A | 1: 1A rated, 0: 5A rated |
| 10.5 | Current Blocking Setting | 0.1～99.99A | 0.01A | Current blocking threshold value |
Outline and Installation Dimensions
FAQ
Q:How does capacitor differential voltage protection work?
A:It detects unbalanced voltage difference across capacitor banks and trips promptly once exceeding threshold to isolate faulty capacitors.
Q:What is the installation mode of capacitor differential voltage protection device?
A:The capacitor differential voltage protection device is generally mounted on switchgear or assembled into panels per project requirements.
Q: What is Capacitor Differential Voltage Protection?
A: It is a dedicated protection for capacitor banks. It monitors the voltage difference between two capacitor branches. When internal series capacitor elements break down and short-circuit, the voltage imbalance triggers tripping to prevent capacitor overvoltage burst and fire hazards.
Q: How does differential voltage protection work?
A: Two groups of series capacitors form two parallel branches. Voltage transformers extract branch voltages and send signals to the relay. Once the voltage deviation exceeds the fixed threshold, the protection judges an internal fault and trips the circuit breaker.
Q: Where is this protection applied?
A: Mainly for high-voltage shunt capacitor banks with multi-series sections, used in substation reactive power compensation cabinets and power factor correction devices.
Q: Why adopt differential voltage instead of overcurrent protection only?
A: Overcurrent protection cannot detect early single element breakdown inside the capacitor string. Differential voltage protection catches slight voltage unbalance at the initial fault stage with high sensitivity, avoiding cascading breakdown of the entire capacitor group.
Q: Key setting principles for differential voltage threshold
A: The pickup value must be higher than normal unbalanced voltage caused by manufacturing tolerance and ambient temperature; meanwhile it shall be lower than the dangerous overvoltage that damages remaining healthy capacitors. A short time delay is added to block transient fluctuation misoperation.
Q: PT wiring mandatory rules
A: Voltage transformers must be strictly matched for two branches with same ratio; PT secondary circuits cannot be open-circuited. Each PT secondary side shall be reliably grounded at one point only.
Q: What happens if PT polarity is reversed?
A: The calculated differential voltage is abnormal, leading to constant protection alarm or incorrect tripping under normal operation. Polarity inspection is required during commissioning.
Q: Protection misoperates without actual capacitor fault
A: Common causes: PT wiring loose/reversed, inconsistent PT accuracy, serious three-phase system voltage unbalance, harmonic distortion. Solutions: check wiring, calibrate PT, increase proper delay.
Q: Protection fails to trip during capacitor internal fault
A: Possible reasons: setting value too large, PT secondary open circuit, signal cable breakage, relay channel failure. Inspect loop continuity and recheck protection parameters.
Q: Tripping occurs after capacitor bank switching on
A: Inrush voltage transient causes momentary imbalance. Enable inrush blocking function or extend short delay to avoid malfunction.
Q: Can it work with other capacitor protections?
A: Yes. It is normally used together with overcurrent protection, zero-sequence earth fault protection and overvoltage protection as a complete protection scheme for capacitor banks.
Q: Routine inspection items
A: Regularly check PT insulation and wiring tightness; test differential voltage reading under no-load state; back up protection setting values; clean dust on voltage acquisition terminals.
3 reviews for 87V Capacitor Differential Voltage Protection | Voltage Unbalance Protection for Capacitor Banks
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xiao zhang –
Capacitor differential voltage protection reliably detects internal breakdown of series capacitor elements via voltage deviation monitoring, with stable anti-interference performance to prevent capacitor bank explosion. It trips rapidly to isolate faulty branches and guarantee safe operation of reactive power compensation cabinets.
Jack –
Strong anti-interference capability, stable in long-term operation — good product.
Jack –
Easy to install and debug, clear protection logic — worth recommending.