PT / VT Ratio Calculator for Voltage Transformers
Calculate voltage transformer ratio for metering and protection circuits.
Use this PT / VT ratio calculator to determine correct voltage transformer ratio used in protection relays, metering systems, and instrument transformers.
VT / PT Parameters
Primary Side (High Voltage)
Secondary Side (Low Voltage)
VT Multiplier / Ratio
Meter Config
Voltage Transformer Ratio (VTR)
100
x
Input this multiplier into your energy meter / relay
Standard Specification
Nameplate
Nameplate Format
11kV / 110V
Common designation format for VT/PT
Engineering Reference
VTR Formula
VTR = V_primary / V_secondary
Actual Voltage Reading
V_actual = V_meter × VTR
- VTR = Voltage Transformer Ratio
- Vp = Primary Voltage (System)
- Vs = Secondary Voltage (Output)
- Note = For phase-to-ground VTs (e.g. 11kV/√3), the ratio remains the same as phase-to-phase if secondary is also /√3.