Maintaining the Circuit Breaker During Operation

Introduction

The electrical switchboard and all its equipment continue to age whether they operate or not. This aging process is due mainly to environmental influences and operating conditions.

To help ensure that circuit breaker retains the operating and safety characteristics specified in the catalogue for the whole of its service life:

Install the circuit breaker in optimum environmental and operating conditions (described in the following table).
Have routine inspections and regular maintenance done by qualified electrical personnel.

Environmental and Operating Conditions

The environmental conditions previously described, refer to harsh operating environments.

The following table describes the optimum environmental and operating conditions:

Environmental and operating factor	Comments
Temperature	Average annual temperature outside the switchboard: < 25 °C (77 °F).
Loading	Loading remains < 80% of In 24 hours a day.
Harmonics	The harmonic current per phase is < 30% of In.
Humidity	The relative humidity is < 70%.
Corrosive atmosphere (SO₂, NH₃, H₂S, Cl₂, NO₂)	Install the circuit breaker in environmental category 3C1 or 3C2 (IEC/EN 60721-3-3).
Saline environment	Install the circuit breaker in an environment free of salt mist.
Dust	The dust level is low: protect the circuit breaker within a switchboard fitted with filters or IP54 ventilated.
Vibration	Continuous vibration is < 0.2 g.

The maintenance programs apply to optimum environmental and operating conditions. Outside these limits circuit breakers are subject to accelerated aging which can quickly lead to malfunctions.

Regular Preventive Maintenance

Maintenance recommendations for each device are intended to maintain the equipment or subassemblies in a satisfactory operational state for their useful service life.

There are three recommended preventive maintenance programs:

Basic end-user maintenance program
Standard end-user maintenance program
Manufacturer maintenance program

NOTE: Global service plans delivered by Schneider Electric may include maintenance plans for your equipment, with a different wording for maintenance levels:

Basic end-user maintenance in this guide corresponds to Routine maintenance in service plans.
Standard end-user maintenance in this guide corresponds to Intermediate maintenance in service plans.
Manufacturer maintenance remains the same.

The following table summarizes maintenance operations for the three preventive maintenance programs:

Maintenance program	Maintenance description	Performed by
Basic end-user maintenance	Visual inspection and functional testing, replacement of inoperative accessories.	Trained and qualified end-user personnel Trained and qualified maintenance services provider personnel Schneider Electric field service representative
Standard end-user maintenance	Basic end-user maintenance, plus operational servicing and subassembly tests.	Trained and qualified maintenance services provider personnel Schneider Electric field service representative
Manufacturer maintenance	Standard end-user maintenance, plus diagnostics and part replacements by Schneider Electric Services.	Schneider Electric field service representative

If all environmental conditions are more favorable than normal, maintenance intervals can be longer than the ones in normal environmental and operating conditions (for example, Standard end-user maintenance programs can be carried out every 3 years).

If any one of the conditions is more severe, perform maintenance more frequently. For advice, contact Schneider Electric Services.

Functions linked specifically to safety require particular maintenance intervals.

NOTE: Regularly test that the remote safety commands work. For example, test at least every six months.

Maintenance Operations Required

Inspection and servicing chiefly consist of checks and inspections A, E, F, G, and H as defined for the commissioning phase.

CAUTION
HAZARD OF EQUIPMENT DAMAGE Insulation and dielectric strength tests must only be carried out by qualified electrical personnel. Failure to follow these instructions can result in injury or equipment damage.

Maintenance operation mainly consists of checks and inspections A, D, E, F, G, I, and J as defined for the commissioning phase.

Letter - maintenance operation	Maintenance operation	Year 1	Year 2	Year 3	Year 4	Year 5
A	Insulation and dielectric strength tests	✔	✔	✔	✔	✔
E	Inspect mechanical equipment	✔	✔	✔	✔	✔
F	Check connections	✔	✔	✔	✔	✔
–	Measurement of insulation resistance	✔	✔	✔	✔	✔
G	Check mechanical operation NOTE: Check tripping by MN/MX twice a year	✔	✔	✔	✔	✔
–	Replace MN/MX trip releases	–	–	–	–	✔
H	Check trip units	✔	✔	✔	✔	✔
J	Check communication	✔	✔	✔	✔	✔
–	Check the closing time, opening time and voltage release characteristics	✔	✔	✔	✔	✔
K	Clean equipment	✔	✔	✔	✔	✔

For a detailed definition of these operations, contact Schneider Electric Services.

Maintenance Following Short-Circuit Trip

Test a circuit breaker in severe conditions, in accordance with standard IEC/EN 60947-2, to check that it can break a short-circuit current at maximum permissible value three times.

After a short-circuit fault, it is necessary to:

Carefully clean off any traces of black smoke (the particles may be conducting)
Check the power connections and control wires
Operate the circuit breaker several times at no load (at least 5 times)

Replacement of Electric Auxiliary Devices in Photovoltaic Circuit Breakers

Special care is required when adding electric auxiliary devices into circuit breakers for photovoltaic applications.

DANGER
HAZARD OF ELECTRIC SHOCK, explosion or arc flash Isolate the circuit breaker upstream and downstream before removing the front cover. Always use a properly rated voltage sensing device to confirm that power is off. Replace the front cover before turning on power to this equipment. Failure to follow these instructions will result in death or serious injury.