DZ47
Miniature Circuit Breaker

Technical Specifications

The DZ47‑63 is a single family: one case width per pole, one rail mounting, and the rating and the curve set by the bimetal and the magnetic release inside. The table below is the standard platform.

Values above describe the standard DZ47‑63 platform and are given as typical ratings. The rated current and the tripping characteristic of a specific breaker follow the order code. Breaking capacity options and degrees of protection for specific installations are confirmed on the datasheet issued with the quotation.

Tripping Characteristics

The curve is what decides whether the breaker trips on the inrush current of the load it protects. Choosing the wrong curve is the most common cause of nuisance tripping on a circuit that is otherwise correctly rated.

The C curve is the correct default for general distribution. The B curve is used where a long cable run has to be protected against a modest overload, and the D curve only where the closing inrush of the load genuinely exceeds the C curve, because a D curve breaker gives less protection against a low-level fault on the same circuit.

Service Conditions

A miniature breaker works in a distribution board in a wall or a machine enclosure. The ambient temperature around the board, the humidity and the pollution of the room set the working limits.

The thermal calibration refers to +30 °C, so a breaker in a warm plant room carries slightly less than its rated current and one in a cold room slightly more. Where the ambient temperature inside the board is far from +30 °C, a correction is applied to the rating rather than leaving the nominal figure to be read as a working value.

Construction & Operating Principle

Housing and mechanism

The case is a high flame‑retardant, high‑strength engineering plastic moulding, and the moving parts of the mechanism are plastic too. Using moulded parts rather than metal in the mechanism keeps the moment of inertia low, so the toggle reaches the latch quickly after a fault is detected. The result is the short total operating time that a modern miniature breaker depends on. The case is sealed in service and the contacts cannot be inspected or replaced: when the breaker reaches the end of its electrical life it is replaced, not repaired.

Contact system and arc quenching

The contact system is current limiting: as the contacts separate under a fault, the electrodynamic force between them pushes them further apart, so the arc is drawn and extinguished quickly and the peak let‑through current is reduced. The arc is driven magnetically into a quenching chamber to be cooled and split. That combination is what allows a breaker only one module wide to reach a breaking capacity of 4500 or 6000 A.

Trip assembly

Overload protection comes from a bimetal strip carrying the circuit current. The strip bends as it heats, and above about 1.13 times the rated current it eventually reaches the latch; the higher the current, the faster it gets there. That is the inverse‑time characteristic described in the table above. Short‑circuit protection comes from a separate electromagnetic release that operates immediately once the current reaches the multiple of In fixed by the curve. Because the two elements are independent, the breaker protects both against a gradual overload and against a fault.

What the breaker does not do

A DZ47 is an overcurrent device. It is not a residual current device, so it does not protect a person against electric shock and it does not detect an earth‑leakage fault on its own. Where that protection is required, an RCD or an RCBO is used, and the DZ47 sits behind it as the overcurrent device. It is also not a switch‑disconnector for isolation purposes beyond the occasional operation for which it is rated: for a circuit that has to be isolated regularly, a proper switch‑disconnector or an isolation device is used.

Poles, Curves & Selecting The Right Rating

Choosing the pole version

A 1P breaker protects a single‑phase circuit and switches only the phase, so the neutral stays solid and the circuit is not fully isolated. A 1P+N switches the neutral as well, which is what a single‑phase circuit needs where the neutral has to be broken for maintenance. A 2P protects a single‑phase circuit in a system where both conductors are live to earth, or a DC circuit. A 3P protects a three‑phase circuit without neutral and a 4P or 3P+N protects one with a neutral that has to be switched.

Choosing the curve

The C curve is the general‑purpose choice for distribution: it tolerates the modest inrush of a fluorescent lighting circuit or a small motor while still tripping quickly on a fault. The B curve is used where a long cable run makes a low‑level earth fault likely and the circuit has to be cleared quickly, and where the load has almost no inrush. The D curve is reserved for loads with a genuinely high inrush —a small transformer energised from the board, a large motor, or a group of lamps —because it gives up sensitivity at the bottom of its magnetic range to get there.

Choosing the rating

The rating is chosen so that the circuit's design current is at or below the breaker rating and the breaker rating is at or below the current‑carrying capacity of the cable. Both halves matter: a breaker rated above the cable capacity protects the load but leaves the cable able to overheat, and one rated below the design current trips in normal service. The breaking capacity then has to exceed the prospective short‑circuit current at the point where the breaker is fitted.

Grading through the installation

The miniature breaker is the bottom of the chain. The GHM3 moulded case breaker above it is set to trip more slowly at the current levels where the DZ47 operates, so a fault on a single final circuit trips only that circuit. The GHW3 air circuit breaker at the incomer holds the fault for the short‑time delay while the two below it clear their own zones. Selecting the three families together, with their settings calculated as a set, is what produces a board where a fault on one socket does not darken the building.

Ratings & Options

Four groups of ratings cover almost every final circuit and small sub‑main in a normal installation, and the pole version and curve are chosen separately from the rating.

The order code combines the model, the pole count, the curve and the rating, for example DZ47-63, 1 pole, C curve, 20 A. Quoting against that form avoids the most common error in ordering miniature breakers, which is a correct rating supplied on the wrong curve.

Key Features

Applications

The DZ47 is used wherever a final circuit or a small sub‑main has to be protected against overload and short circuit — which in practice means every distribution board in a building and most machine panels.

What We Need to Quote Your Breaker

The rating, the pole version and the curve are all needed together — a correct rating on the wrong curve is the most common ordering error. With the items below we can return a firm quotation.

Send these to gohointl@gmail.com and we will reply with a priced offer, the curve and rating confirmation, and the routine test plan for the breakers.

Standards & Documentation

Type test reports for the DZ47‑63 platform and the routine test record for the individual breaker are available for project qualification on request.

Breakers are assembled in our own factory in Yueqing, Zhejiang — the same site that builds our switchgear, transformers and prefabricated substations. Case assembly, release fitting and calibration, and routine testing all happen in‑house, which keeps both the delivery schedule and the quality check inside our control.