Siemens WL - Page 62

Technical Data for Voltage Transformers
WL Circuit Breaker
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WL Selection and Application Guide • 2005
VT / PT Connections for the WL Breaker when equipped with Metering
(WLMETER, WLMETERP)
The metering module (“Meter
Function”) can be set to expect
3W or 4W (LL/LG) connections
and will adjust the amplitude
and phase of the signal as
necessary.
The trip unit settings which
must be made are:
1) VT Primary Voltage (240V,
480V, 600V)
2) VT Secondary Voltage
(100V, 110V, 120V)
3) VT Connection (Wye / LG,
Delta / LL)
Three VTs must be used at all
times.
All three VTs should be rated for
the nominal system L-L voltage
(e.g. 480V) and may have either
100V, 110V or 120V secondary
voltages.
The following ratios and
suggested and equivalent VTs
can be used:
240:120 = 2:1
(ITI Part # 460-240 or 468-240)
480:120 = 4:1
(ITI Part # 460-480 or 468-480)
600:120 = 5:1
(ITI Part # 460-600 or 468-600)
VT Accuracy:
Each Metering Module presents
a purely resistive (unity power
factor) load to the transformer.
Assuming no other devices
connected to the VT, a ITI type
486 VT can safely feed 10
metering modules and and still
maintain 0.6% accuracy
assuming the wiring from the
VT to the individual metering
modules is twisted pair and
kept to a minimum length.
Metering VT Settings:
Delta/Wye : Delta
VT Primary: 480 (for example)
VT Secondary: 120 (for example)
Note: Required primary and secondary overcurrent protection (fusing)
not shown for clarity.
Metering VT Settings:
Delta/Wye : Delta
VT Primary: 480 (for example)
VT Secondary: 120 (for example)
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