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PERIODIC INSPECTION.

INSPECTIONS MUST BE PERFORMED VERY CAREFULLY IN ORDER TO AVOID ANY ACCIDENT !!!

If the breaker trips open automatically, remove the cause of tripping operation before returning the operating handle to the ON position.

If the breaker tripped due to a short-circuit current, check the breaker carefully. Otherwise, a fire could result.

Do not touch terminals and/or molded parts close to terminals immediately after switch to OFF position. Doing so may cause burns.

There are two types of inspections: INITIAL (before placing the breaker in service) and PERIODIC.

INITIAL INSPECTION.

Before placing the installed breaker in service, make sure that:

 

- Packing materials, iron chipping, wire pieces, or other conductive foreign objects do not remain inside the breaker.

- The cover and base are not cracked or damaged.

- Terminal screws and wire clamp screws are securely tightened.

- The rated voltage and breaking capacity of the breaker are suited to the application

- The operating handle can be operated normally

- If the breaker has been stored for a long time, try to move operating handle to the ON/OFF position several times to check for smooth close/open operation).

IF THE OPERATING HANDLE CANNOT BE HELD AT THE OFF POSITION, REPLACE THE BREAKER WITHOUT DELAY. THE REASON MAY IMPLY THAT CONTACTS HAVE BEEN DAMAGED OR THE OPERATING MECHANISM MALFUNCTION.

PERIODIC INSPECTION.

In addition to initial inspection to be conducted approx. one month after the breaker is placed in service, periodic inspection of breaker is needed at intervals depending on service condition.

Suggested intervals:

 

- Within 10 years after installation: Every two or three years.

- More than 10 years after installation: Every year.

- More than 15 years after installation; Every six months.

Be sure to move operating handle to OFF or TRIP position before installing or removing the breaker.

When overcurrent flows through the breaker or UVT is actuated or the TRIP button is pressed, the breaker contacts open and the operating handle moves to a halfway position between the ON and OFF positions. Moving the handle from the halfway position to the ON position will not cause the breaker to close.

The trip button located on the cover should be used to check the tripping mechanism for normal operation. Pressing this button will force the breaker to trip open.

CAUTION!!! DO NOT USE THE TRIP BUTTON TO OPEN THE BREAKERUNDER LOAD!!!

To close the breaker that has trip open, the following reset operation is needed. Move the operating handle from the TRIP position down to RESET position, release the handle and it will be held at the OFF position. Then you can switch ON breaker by moving operating handle to ON position. If the beaker equipped with UVT device, the voltage to UVT must be applied before switch to ON position, otherwise the breaker will trip again.



 

CAUTION!!! If the breaker trips due to an overload, it may not accept RESET operation, wait for a few minutes (one to four minutes) until the bimetal cools down and then retry to reset the breaker.

IF THE OPERATING HANDLE CANNOT BE HELD AT THE OFF POSITION, REPLACE THE BREAKER WITHOUT DELAY. THE REASON MAY IMPLY THAT CONTACTS HAVE BEEN DAMAGED OR THE OPERATING MECHANISM MALFUNCTION.

When it is required to open the breaker cover during inspection of internal mechanisms or contacts, remove the breaker from the switchboard before opening the cover. Otherwise, internal parts could drop off!

 

As is the same with other electrical equipment, breakers need initial inspection and periodic inspection in order to prevent performance deterioration and accidents. Breakers also require inspection when they malfunctions and after they interrupted a short-circuit current.

 

 

The following table shows inspection items and care during a periodic inspection.

Inspection item Procedure Care
Loose terminals Check terminal screw and wire clamp screw for looseness Tighten the screws to the specified tightening torque (see makers instruction manual). Take care not to tighten excessively.
Dust Check breaker surfaces, particularly the top line side surfaces, for accumulation of dust. Remove dust or foreign materials using a cleaner and wipe clean with a dry, clean cloth. Do not use a thinner or detergent!!!
Damage to molded case Check the breaker cover and base for damage or cracks. Replace with a new breaker
Arc chutes Check arc chutes for contamination Replace with a new chutes or breaker if excessive contamination with spot of molten metal particles is found
Contacts condition Check contacts surface Blackening of contact tip surfaces is due to oxidation and subformation and will not lead to any problems since it wiped off by quick-dry contact cleaner and soft rags. Remove dirt, dust, grease, etc. If thickness of contacts is reduced to of original value, replaces breaker
Insulation resistance Isolate all connecting conductors from the breaker and measure the insulation resistance between phases Replace with a new breaker if the insulation resistance is less than 5MOm

 


Date: 2015-12-24; view: 717


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