doble TDR900 - Connect Test Leads to Breaker; Overall Test (Dead Tank or OCB Test); Figure 11. General Control Schematic

Doble TDR900 User Guide
72A-2612-01 Rev. A 09/06
21
5.5 Connect Test Leads to Breaker
Connect the safety ground to the breaker and to the Doble TDR900 test set.
Caution: No contact test leads (Sectional EHV or Overall OCB) should be attached
to the breaker if it is still on load or energized.
Only authorized and qualified personnel should perform the lead connection for off-line
tests. The DC power knife switches or disconnects within the Breaker Control cabinet
should be opened before any leads are connected.
For off-line tests only: Connect either OCB or EHV leads, and any other leads or
transducers which are required for the desired breaker test.
A general control schematic is given in Figure 11. The Doble Breaker Control Cable
should have its two “Trip” leads connected across the Trip switch on the breaker; the two
“Close” clips should be attached across the Close switch on the breaker.
Figure 11. General Control Schematic
Caution: To minimize the chance of the conductors becoming energized due to static
electricity, Doble Engineering Company recommends attaching all test set leads
to the instrument while the other end of the leads are still on the ground.
Attaching the leads to the transformer bushings first increases the risk of
operator injury.
5.5.1 Overall Test (Dead Tank or OCB test)
The Sectional test is also known as an OCB test or Dead Tank test. One test cable is used
and connected to the first connector on the left of the top Main Contacts set.
Three bushings on one side of the breaker should be common to each other and
grounded; the other three bushings should be disconnected from ground, as in Figure 12.