TAVRIDA ELECTRIC ISM_LD Series, Application Manual

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1
Closing
In the open position the contacts are kept open by the force of the opening springs. To close
the contacts the coils of the magnetic actuators are excited by a current impulse from the close
capacitors of the CM. The opening springs are compressed when the contacts close. In the closed
position the contacts are kept closed only by means of the magnetic force. The ISM maintains the
closed position without mechanical latching even in the event of a failure of the auxiliary power
supply (Figure 5).
Opening
To open the contacts a current impulse in the reverse polarity derived from the opening capacitors
of the CM is injected in the coils of the magnetic actuators, releasing the magnetic holding force.
The compressed opening springs and contact pressure springs open the contacts (Figure 5).
Manual-Emergency-Tripping
The ISM can also be manually opened. When the synchronizing shaft is rotated, a force exceeding
the magnetic attraction forces of the ring magnet is applied to the armature, which subseqently
starts to move. As the air gap increases, the opening springs and the contact pressure springs
overcome the magnetic holding force, and the vacuum interrupter opens.
Manual Closing
The ISM can only be closed electrically via the CM. In the case of a failure of auxiliary power
supply the contacts can be closed using an alternative auxiliary power supply such as a battery.
Mechanical closing is not possible and leads to the destruction of the ISM.
Position main
contacts
Actuator coil
current
Anchor travel
Anchor velocity
Open
Closed
Open
Closed
0
0
0
Close comm
an
d CM (d
ry con
tact)
Close impuls to I
SM-coils
Start an
ch
or m
ovem
en
t
ISM m
ain con
tacts closed
Stop an
ch
or m
ovem
en
t
Switch o
ff actu
ator
curr
en
t f
or close oper
ati
on
Trip comm
an
d CM
(d
ry con
tact)
Trip impuls to I
SM-coils
ISM m
ain con
tacts open
Open positi
on k
ept by
openin
g sprin
gs
0 20 40 60 80 100 120 140 160
Time (ms)
1
Figure 5
Typical oscillogram of ISM operation