Instruction Leaflet IL0102002E
Effective April 2018
Ring Main Unit Operation Instruction
31EATON CORPORATION www.eaton.com
2.1. Patrol inspection
This mainly refers to appearance inspection on the equipment
during operation. Make a visual check for any abnormal conditions,
on a daily or weekly basis, or according to the enterprise standard
of the using unit.
2.2. General inspection
This refers to the general inspection and maintenance from the
outside when the RMU is stopped for running.
2.3. Regular inspection
This refers to detailed inspection and maintenance from the
outside when the RMU is stopped for running.
2. Maintenance and repair
The RMU shall be maintained and repaired as specified in
relevant regulations. Generally, there are four different
inspections, including patrol inspection, general inspection,
regular inspection and temporary maintenance.
Item RemarkInspection content
External conditions of the equipment 1. The indication status of the breaking-closing indicator;
2. Whether there is abnormal sound or odor;
3. Whether the HV presence display is normal
4. Whether the external surface of the cable is damaged
5. The indication status of SF6 pressure meter
Spring operating mechanism 1. Whether the breaking-closing indication is correct
Item Inspection content Period Remark
Mechanical operation test 1. Opening and closing indication status
2. Opening/closing time measurement to check for any
exceptions
3. To confirm whether the indication meter is working
properly
4. To check whether the secondary circuit wiring is loose
5. Lubrication and cleaning
Once every 3 years.
Fuse To measure the changes of internal resistance of the fuse Once every 3 years
External connections To check the fastening status of the sealing parts Once every 3 years Mechanical inspection
Testing To measure circuit resistance and see whether there are
any abnormal changes.
Once every 3 years Electrical inspection
Item Inspection content Period Remark
Mechanical operation test 1. Opening and closing indication status
2. To check whether the mechanisms and the pins and
shafts of each part are normal
3. To replace or repair the corrosive, deformed and
damaged parts in the operating mechanism
4. To confirm whether the indication meter is working properly
5. To check whether the secondary circuit wiring is loose
6. Lubrication and cleaning
Once every 12 years
Fuse To measure the changes of the internal resistance of the fuse Once every 12 years
External connections To check the fastening status of the sealing parts Once every 12 years Mechanical inspection
Testing To measure the circuit resistance and see whether there
are any abnormal changes;
Opening/closing operation characteristics test
Once every 12 years Electrical inspection
Conduct manual opening-closing
operation once every year, if the
switch is not operated frequently
The change of the inner
resistance variations shall be
within ±10%
The change of the inner
resistance variations shall be
within±10%
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