Siemens 3TM Betriebsanleitung - Seite 37
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Maintenance
Inspections
Checking the switching
stroke of vacuum
interrupters
9229 0098 176 0-
2019-01-09
Maintenance and servicing
DANGER
Risk of injury!
Working on the opened and closed vacuum contactor can lead to fatal injuries.
•
Before beginning maintenance work, note the 5 safety rules for high-voltage
equipment specified in EN 50110-1, namely:
- Isolate from the power supply
- Secure against reclosing
- Verify that the equipment has been de-energised
- Earth and short-circuit
- Cover or cordon off neighbouring live parts
•
Open the vacuum contactor by hand and operate the mechanical unlatching
if necessary. This ensures that the vacuum contactor is open.
•
The vacuum contactor is to be taken out of the system/switch cabinet for
maintenance work.
The following work is to be carried out as part of the regular inspections:
•
Visual inspections during storage, see "Storage" on p. 7
•
Visual inspections during operation
•
Screws and terminals are firmly attached
•
Earthing connection firmly established and not damaged
•
Labelling is clearly legible
•
Insulation capacity not hampered by deposits, see "Cleaning" on p. 39
•
Check the limit dimension of switching stroke of the vacuum interrupters,
depending on the mechanical and electrical strain or switching frequency, every
100,000 switch operations or once a year. See "Checking the switching stroke
of vacuum interrupters" on p. 37
•
Regular function check of closing latching and then unlatching with manual trip,
see "Mechanical closing latching", on p. 16
•
Measurement of conductance of auxiliary switch contacts.
Reliable switching of the 3TM vacuum contactor is only ensured if the switching
stroke of the vacuum interrupters is not below the minimum of 3.5 mm and does not
exceed the maximum of 7.5 mm.
The switching stroke can vary depending on current, elapsed service life, and
switching frequency. If the value goes below the limit, arcing between the contacts
in the vacuum interrupter can negatively affect opening.
Correct functioning of the bellows for the vacuum interrupters can be compromised
if the limit is violated.
The switching stroke must be regularly checked. If the limit is reached, the switching
stroke can be readjusted once.
If the limit is then exceeded again, the vacuum contactor must be replaced.
If the specified limits for mechanical or electrical service life are reached, the vacu-
um contactor must be replaced and readjustment is not permissible.
Maintenance
37