701 Motor Protection Relay Date Code 20010719
Settings Calculation
General Data
4.6
Voltage Transformer (VT)
Configuration Settings (Relay Models 0701001X & 0701011X)
Table 4.4 VT Co nfiguration Set tings
These settings configure the optional relay voltage inputs to correctly measure
and scale the voltage signals. Set the Phase VT Ratio (PTR) setting equal to the VT
ratio to 1.
EXAMPLE 4.2 Phase VT Ratio Setting Calculations
Consider a 4160 V motor application where the phase-to-phase
connected voltage transformer ratios are 4160:118.
Set PTR = 4160/118 = 35.25 = 35
When phase-to-phase potentials are connected to the relay, set DELTA_Y equal
to D. When phase-to-neutral potentials are connected to the relay, set DELTA_Y equal
to Y.
In applications where only a single voltage is available, set SINGLEVequal to Y.
As shown in Figure 2.8 on page 2.9 in Section 2: Installation and Figure 2.9 on
page 2.9 in Section 2: Installation, the single voltage must be connected to the A-phase
input, but it may be an A-N or an A-B voltage. Be sure to set DELTA_Y equal to Y for
an A-N input or DELTA_Y equal to D for an A-B input voltage.
When you set SINGLEV equal to Y, the relay performance changes in the
following ways:
Voltage Elements. When you use one phase-to-phase voltage, the
relay overvoltage and undervoltage elements use the applied phase-
to-phase voltage only. When you use one phase-to-neutral voltage,
the relay voltage elements use the applied phase-to-neutral voltage
only.
Power Elements. When you use one voltage, the relay assumes that
the system voltages are balanced in both magnitude and phase angle
to calculate apparent, real, and reactive power and the power factor.
Metering. When you use one phase-to-phase voltage, the relay
displays that magnitude and phase angle. When you use one phase-
to-neutral voltage, the relay multiplies that magnitude by the square-
root of three to calculate an approximate phase-to-phase voltage for
Table 4.4 VT Configuration Settings
Setting Prompt
Setting Range
Setting Name =
Factory Default
Phase (VA, VB, VC) VT Ratio 1–6000 PTR = 100
Phase VT Connection D, Y DELTA_Y = Y
Single Voltage Input Y, N SINGLEV = N
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