Contacts
All movable and main stationary contacts employ
copper-tungsten alloy tips at points subjected to arcing
duty. Contact points not subjected to arcing employ a
combination of EPT copper to provide a high conductivity
current path. Movable contacts are split to make contact
on both sides of mating parts and resist separation during
high current surges. Contact pressure is maintained by steel
compression springs.
Main stationary contacts
The main stationary contact is used for stationary tap
contacts and the neutral contact.
Main movable contacts
The main movable contact assembly is made up of a set
of two individual contact assemblies and a thermal set
material insulating arm. Each of the main movable contacts
makes contact with the main stationary contacts as the
tap changer rotates through each tap position. At least one
of the main movable contacts remains in contact with a
stationary contact at all times. The main stationary contacts
bolt to collector rings. The collector rings insert between
a set of button contacts that are able to hold a continuous
current path through all 32 steps of the tap changer and
while in neutral. The movable contact assemblies are
identical and can be used for either the right or left hand
contacts.
Reversing stationary contacts
The set of reversing switch stationary contacts on the QD5
tap-changer consist of three individual stationary contacts,
a VL-Reversing Stationary, a Reversing Neutral Stationary,
and a VR-Reversing Raise Stationary contact. The reversing
switch stationary contacts see less operating duty than the
main stationary contacts and therefore do not utilize the
copper-tungsten alloy arcing tips.
Figure 5. Main movable contact assembly.
Figure 6. VL reversing
stationary.
Figure 7. Figure 8. Neutral reversing
stationary.
Figure 8. Figure 7. VR
reversing stationary.
Figure 4. Main stationary contact.
Copper-Tungsten
Arcing Tips
3
QD5 QUIK-DRIVE TAP-CHANGER INSTALLATION AND MAINTENANCE INSTRUCTIONS MN225012EN March 2016
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