Quelle est la différence entre le Type B, le Type B+ et le Type B-HP ?

Within the UK Wiring Regulations (BS 7671) and IEC standards (IEC/EN 62423), these types are distinctly defined. Their core difference lies in the types of residual current waveforms they can detect and respond to.

Pour construire un modèle conceptuel rapide :

• Type B: The foundational all-rounder, covering AC, pulsating DC, and smooth DC.

• Type B+: Enhances the Type B by improving its response to high-frequency residual currents.

• Type B-HP: Builds on Type B+ by offering superior resistance to nuisance tripping from high-frequency currents, representing the current peak of performance.

Examinons les détails.

1. RCD Type B (Standard Type B)

Le Type B est le DDR « polyvalent » fondamental pour gérer les composantes de défaut DC complexes. C’est un sur-ensemble du Type A.

• Formes d’onde qu’il peut détecter :

  1. AC Residual Current (Type AC functionality): Standard power frequency (50Hz) leakage.

  2. Pulsating DC Residual Current (Type A functionality): e.g., from half-wave rectification or simple switch-mode power supplies.

  3. Smooth DC Residual Current (Core Type B functionality): This is the key differentiator from Type A. It can detect and interrupt a persistent smooth DC fault current, preventing the RCD from being « blinded. »

• How it works: It uses a special internal design (often involving a tuned circuit) to reliably operate for AC residual currents from DC up to 1kHz, and can also detect smooth DC.

• Applications typiques (selon la BS 7671) :

  • Équipements entraînés par des variateurs de vitesse triphasés (ascenseurs, pompes industrielles, compresseurs de CVC).

  • Electric Vehicle (EV) Charging Points (often a mandatory requirement under BS 7671 Section 722).

  • Le côté sortie des grands systèmes UPS et des onduleurs PV.

  • Équipements de radiographie, équipements d’imagerie médicale.

2. RCD Type B+ (Type B Enhanced)

Type B+ is an evolved version of Type B. It inherits all the standard Type B functions and significantly enhances its sensitivity to high-frequency residual currents.

• Formes d’onde qu’il peut détecter : Includes all Type B functions, plus:

  • Reliable response to high-frequency residual currents up to 20kHz. The response of a standard Type B drops off sharply above 1kHz.

• Why is this needed? Modern switch-mode power supply technologies (like LLC resonant converters, Totem-Pole PFC) operate at increasingly higher frequencies, commonly found in:

  • Dernière génération de points de recharge VE haute efficacité

  • Alimentations de serveurs, équipements IT haut de gamme

  • LED drivers

  • Variateurs de vitesse industriels (topologies plus avancées)
    Si ces appareils développent un défaut de terre haute fréquence, un Type B standard pourrait ne pas le détecter ou ne pas se déclencher assez rapidement. Le Type B+ comble cette lacune de sécurité.

3. RCD Type B-HP (Élevé-Performance Type B)

Type B-HP is the top-tier product in the current RCD technology landscape. It builds upon Type B+ by adding one critical feature: immunity to nuisance tripping from high-frequency currents.

• Formes d’onde qu’il peut détecter : Fully encompasses all Type B+ functions.

• Fonctionnalité supplémentaire clé :

  • It can not only reliably detect fault currents at frequencies up to 20kHz (or even higher, e.g., 50kHz), but it can also differentiate between dangerous fault currents and tolerable high-frequency leakage currents present during normal equipment operation.

  • Modern equipment, especially high-power chargers and industrial drives, inherently generates some high-frequency common-mode leakage during normal operation. A less performant RCD might misinterpret this normal leakage as a fault, causing a nuisance trip and resulting in an unnecessary power outage.

• How it works: B-HP RCDs incorporate more complex filtering and signal processing circuits. Their frequency-tripping current characteristic curve is meticulously designed for greater stability at high frequencies, ensuring operation only under genuinely dangerous fault conditions.

• Applications typiques :

  • Immunité haute fréquence pour les fuites d’onduleur/pompe à chaleur

  • Latest, highest-power Electric Vehicle charging equipment (this is the primary application for B-HP).

  • Installations critiques où la continuité de l’alimentation est primordiale (ex. centres de données, salles d’opération).

  • Lignes de production et grosses machines utilisant la technologie de variation de vitesse la plus avancée.

Résumé et comparaison

Pour une comparaison claire d’un coup d’œil, veuillez vous référer au tableau ci-dessous :

Conseils pour les ingénieurs électriques britanniques

1. Comply with Regulations: When designing an installation, your primary and mandatory duty is to follow the latest edition of BS 7671 and any relevant equipment manufacturers’ technical requirements. For instance, selecting an RCD for an pompe à chaleur devrait utiliser un Type B-HP.

2. Consult Manufacturers: The manufacturer of electrical equipment (especially drives, chargers) will explicitly specify the required RCD type in its installation manual. Always treat the manufacturer’s instructions as the final authority.

3. Trend: As technology evolves, Type B+ and Type B-HP are increasingly becoming the standard choice for protecting advanced power electronic equipment, particularly in commercial and industrial settings. Due to its superior stability, Type B-HP is becoming the preferred choice for high-end applications to minimise operational disruptions from nuisance tripping.