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УЗО типа B: защита от сбоев при постоянном токе и руководство по выбору
What is a Type B RCCB, and when is smooth DC fault detection needed? Compare RCD types, check upstream coordination, and use a practical specification checklist.
Краткий ответ: A Type B RCCB is a residual-current circuit breaker designed to detect sinusoidal AC, pulsating DC and smooth DC residual currents within its specified limits. It is worth considering when a connected converter, drive, inverter or charger can produce DC earth-fault current. The equipment manual, local installation rules and the exact RCCB datasheet determine the final choice.
What Does “Type B” Mean?
RCD type describes the residual-current waveforms a device is intended to detect. IEC 62423 specifies additional requirements and tests for Type F and Type B RCDs. Type B devices include detection of smooth DC residual current as well as the AC and pulsating DC waveforms covered by Type A. A Type B marking does not by itself establish the correct current rating, sensitivity, poles or suitability for every installation.
| Тип УЗО | Relevant residual-current capability | Selection question |
|---|---|---|
| Тип AC | Синусоидальный переменный ток | Do the equipment instructions and local rules permit it for the circuit? |
| Тип A | Sinusoidal AC and pulsating DC | Could smooth DC residual current occur beyond its intended tolerance? |
| Тип F | Type A capability plus specified composite currents from certain single-phase converters | Is the circuit a suitable single-phase inverter application? |
| Тип B | Includes smooth DC residual-current detection | Does the equipment or applicable rule require Type B, and is the chosen model correctly rated? |
When Might a Type B RCCB Be Needed?
Power electronic equipment such as some variable-speed drives, photovoltaic inverters and EV charging systems can create DC earth leakage or DC fault current. The presence of an inverter alone is not enough to prescribe Type B. Some equipment includes its own DC fault detection, and some installation rules permit another arrangement. Read the exact equipment manual and the rules for the destination market before choosing a device.
For EV charging, for example, a Type B RCD is one possible solution; a suitable Type A or F RCD combined with a 6 mA DC residual-current detecting device may also be allowed under the applicable design rules. See Schneider Electric’s guide to RCD selection where DC earth leakage is present. Do not treat this example as a universal wiring instruction.
Check the Upstream RCD as Well
A downstream Type B device can allow a certain DC residual current to pass before it trips. That current may affect a non-Type-B RCD upstream or elsewhere in the installation. The designer must review the earthing system, the position of RCDs and their coordination. Replacing only the final-circuit RCD may leave an upstream device exposed to DC current. Schneider Electric explains this RCD blinding and coordination issue with circuit examples.
RCCB Is Not Overcurrent Protection
An RCCB responds to residual current. It does not replace the circuit’s short-circuit and overload protection. Coordinate it with an appropriate upstream circuit breaker or fuse, and check the prospective fault current and the manufacturer’s conditional short-circuit data. If a combined device is required, compare an RCBO instead. Our RCD coordination guide discusses selectivity in more detail.
What to Check Before Ordering
- Connected equipment: model number, installation manual and any integrated DC fault monitoring.
- Supply and earthing: voltage, phases, neutral and earthing arrangement.
- Residual-current type: Type A, F or B as required by the equipment and local rules.
- Rated current and poles: match the circuit design and the device datasheet.
- Residual operating current: select sensitivity for the protection objective and expected normal leakage.
- Fault-current coordination: verify the upstream protective device and prospective short-circuit current.
- Upstream RCDs: assess possible DC blinding and selectivity.
- Доказательства: request the current datasheet and applicable test or certification documents for the exact order code.
KUANGYA lists a VKL11 B/B+ RCCB product page with available pole and sensitivity options. Use that page as a starting point, then confirm the exact variant and documentation before specifying or ordering. For a quotation, send your equipment manual and the checks above through our contact form.
Часто задаваемые вопросы
Does every inverter need a Type B RCCB?
No. The fault-current characteristics, integrated monitoring, equipment instructions and local rules decide the required protection.
Can Type A detect smooth DC residual current like Type B?
No. Type A is intended for sinusoidal AC and pulsating DC residual current. If smooth DC fault detection is required, use a compliant protective arrangement specified for that duty.
Is Type B always the safest upgrade?
No single RCD type solves every design problem. Sensitivity, rated current, fault-current capacity, upstream coordination and correct installation still matter.
Does a Type B RCCB also protect against overload?
No. An RCCB needs suitable overcurrent protection. An RCBO combines residual-current and overcurrent functions in one device.
