Circuit Breaker

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LV Circuit Breakers

Over 80 nations who are co-operating to formulate world standards on electrical supply and harmonization have comprised International Electrotechnical Commission (IEC). However, most of these participating countries already have their own national standards which might differ from elements of IEC standards.

At Quality Defender, we mainly adopt European Standards (EN) and British Standards (BS) when doing test for low voltage circuit breakers. These standards include BS EN 61439-3-2012(2015): Low-voltage switchgear and control gear assemblies; BS EN 60898-1-2019: Electrical accessories - Circuit breakers for overcurrent protection for household and similar installations - Part 1: Circuit-breakers for a.c. operation; BS EN 61008: Residual current operated circuit-breakers without integral overcurrent protection for household and similar uses (RCCB's) and BS EN 61009:  Residual current operated circuit-breakers with integral overcurrent protection for household and similar uses (RCBOs)



Our general inspection procedure on the LV circuit breakers consists below points.

However we are open to customized testing requirements.

Check List
Quantity Check- QTY must be checked according to the PO.
Packaging Quality- Check the sturdiness of the boxes. Make sure no excess space wasted.
Artwork and Labels- The labels, description and line drawings shall match the actual products
Instruction Manual- Check if there is any errors on the instruction manual/wiring Diagram.
Indelibility of Marking- All the markings on the products shall be correct and permanently durable and legible, and shall not be placed on screws, removable washers or other easily removable parts, or upon parts intended for separate sale.
SN /PO Number- SN/PO numbers shall be printed on the reversed sides of the products
Visual inspection on the product surface and structure- The product surface shall be smooth with no obvious scratches, rust, or any damages
- Inner parts, no sharp edges, cracks/breaks, rust and burrs are allowed.
Compliance of CE and WEEE Symbol
The minimum size is the diagonal X is 5.00mm. Ideally this mark should be moulded in the plastic if a suitable place can be found on the reverse of the face plates.
Material, Colour and finish consistency- Check the material used on the products should be up to the specification
- Carefully check the case color and finish and make sure they are consistent and are good match to reference samples.
- No contamination or mold marks on the surface is allowed.
Pad Printing or Laser Etching Quality- The pad printing or laser etching on the product shall be clean, clear and durable.
Checking of dimensions and weight- Measure the product height, width, depth, distance between din-rail clips, length of flying leads and weight shall be up to requirements.
Mechanical Indicator- If a separate mechanical indicator is used to indicate the position of the main contacts, this shall show the color red for the closed position (ON) and the color green for the open position (OFF), the switching of ON/OFF of indicator needs to be smooth.
Reliabilities of Screws, Current-carrying Parts and Connection- The screws shall be tightened and loosened manually for minimum five times for checking screws engagement with a thread of insulating materials. During the test, the screwed connection shall not work loose and there shall be no damage, such as breakage of screws or damage to the head slots, threads that will impair the further use of the circuit breaker. Torque 2.5Nm for 1min.
Reliabilities of terminals for external conductors- Terminals shall be designed to clamp the conductors reliably..Termimals shall allow the connection of copper conductors having nominal cross-sectional areas.
Terminal Arrangement- Products shall have correct terminal arrangement and all clearly marked  
Switch Operation Check- Manually operate switch (MIN 20 times) to check if switch operate smoothly. No switches shall be stuck or jammed.
Test button (RCCB/RCBO)- Press the test button with product loaded, main contact shall be open.  
Time Current Characteristic Test- Part one (MCB/RCBO)- A current equal to 1.13In is passed for the conventional time through all poles, starting from cold. The circuit breaker shall not trip in 1 hour, the current is then steadily increased within 5s, to 1.45In, the circuit breaker shall trip within the 1 hour.
Time Current Characteristic Test- Part Two (MCB/RCBO)- A current equal to 2.55In is passed through all poles, starting from cold, the opening time shall not be less than 1s and shall not be more than 60s for rated currents up to and including 32A;  120s for rated currents greater than 32A.
Instantaneous tripping test (MCB/RCBO)- For type B, 3In is applied on breaker, the opening time shall be not less than 0.1s and not more than 45s for rating up to 32A, 90s for above 32A. 5In is applied, the breaker shall trip in a time less than 0.1s.
- For type C, 5In is applied on breaker, the opening time shall be not less than 0.1s and not more than 15s for rating up to 32A, 30s for above 32A. 10In is applied, the breaker shall trip in a time less than 0.1s.
- For type D, 10In is applied on breaker, the opening time shall be not less than 0.1s and not more than 4s for rating up to 32A, 8s for above 32A. 20In is applied, the breaker shall trip in a time less than 0.1s.
Residual Current Operation Test- type AC ( RCCB/RCBO)- For type AC RCCB/RCBO, being in the closed position, the residual current is steadily increased, starting from a value not higher than 0,2 I△n, trying to attain the value of I△n within 30 s, the tripping current being measured shall be no higher than the rated residual current.
Residual Pulsating Direct Current- Type A (RCCB/RCBO)- For type A RCCB/RCBO, Verification of correct operation in case of a continuous rise of residual pulsating direct current- Refer to Annex 9.9.31
Type Test For Performance (Isolator)- For isolator: To verify the general performance and characteristic, operational performance, Short circuit performance, conditional short circuit current, over-load performance capacity.
Resistance to Heat- The switchgear is kept for 1h in a heating cabinet at a temperature of (100±2) °C, after the test, there shall be no access to Live part, marking shall still be legible. Discolor, blister or displacement of the case are disregarded.
Resistance to Abnormal heat and Fire- For external parts of switchgear made of insulating material necessary to retain in position current-carry parts and parts of protective circuit, by the test made at a temperature of (960±15)°C.
Resistance to Rusting- Screws are degreased before test, the parts then immersed for 10min in a 10% solution of ammonium chloride in water at a temperature of (20±5)°C, shake drops before placing in an air-saturated with moisture at a temperature of (20±5)°C ,dried for 10min in a heating cabinet at (100±5)°C, the surface shall show no signs of rust.    
EMC Test- To verify switchgear’s compliance with EMC requirement. immunity: switchgear not incorporating electronic circuits
Switch Mechanical Life Test- When time allows and equipment available, on-off mechanical life cycle test shall be carried out at the factory.
High–pot test- High–pot 2.0 KV test
Din-rail installation test- When installed on din-rail, force applied on switchgear, downward vertical 50N for 1 min, upward vertical 50N for 1min, no damage

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