28
ANSI MEDIUM VOLTAGE METAL-CLAD DIGITAL SWITCHGEAR
• Step 3/8
Isolate the whole bus section. All circuit
breakers belong to the relative busbar section
move into the test position.
• Step 4/8
Select one outgoing switchgear frame in the
section to apply voltage on the main bus.
Remove the circuit breaker out of the
switchgear frame and connect all 3 phases to
ground.
• Step 5/8
Except the tested phase, connect all other
phases together to the grounding bar.
• Step 6/8
Connect the tester to the isolated (measured)
phase and grounding bar.
Check voltage values for the phase on the voltage
receiver protection relays LHMI Measurements
view.
The voltage value must be identical with the
voltage sender protection relay and without
brackets around the value.
Since the protection relay is reporting phase-to-
phase voltages, two identical measurements will
appear on the display. For example, if voltage is
applied between phase 1 and the ground, then
the protection relay shows U₁₂ = U₃₁ and U₂₃ = 0.
• Step 7/8
Inject voltage higher than 1% of the primary
(nominal) value.
• Step 8/8
Check voltage metering for the phase on the
voltage sender protection relay LHMI
Measurements view.
—
46 Test setup for
voltage sensors
installed on main bus
—
47 Measurements view,
injected phase 1
—
48 Measurements
view, injected phase 1
—
47
—
47
—
48
• Step 2/8
Caution:
Make sure there is no
voltage on the busbar.
Open the top shutter in the circuit breaker
compartment.
CAUTION
L1
L2
L3
No circuit
breaker
U
Primary
tester
~U (V)