Electrical Current Ratio Guide
Current ratio compares two current values in the same electrical system. It is used in transformer work, current transformer selection, load checking, metering, and fault review. A ratio makes a large current easier to express. It also helps compare measured values against expected design values.
Why Current Ratio Matters
In an ideal transformer, current changes opposite to voltage. A step down transformer raises secondary current. A step up transformer lowers secondary current. The relation helps engineers estimate load current before equipment is energized. It also helps technicians detect winding errors, wrong taps, or faulty instruments.
Current transformers use ratio values for safe metering. A 400:5 current transformer means four hundred amperes on the primary should produce five amperes on the secondary. The meter reads the smaller current. Then it scales the value back to the real line current. This protects instruments and operators.
Advanced Inputs
This calculator accepts primary current, secondary current, voltage values, turns values, burden, power factor, and load data. These inputs support several checks. The measured ratio shows the relation from actual current readings. The voltage ratio predicts the ideal secondary to primary current ratio. The turns ratio gives another expected value. Comparing these numbers shows the percent difference.
Burden is also important. A current transformer must drive meters, relays, and wiring. Burden voltage is found from apparent burden divided by secondary current. Real power and reactive power are estimated from power factor. This helps judge whether the secondary circuit is overloaded.
Practical Notes
Use values from the same test condition. Do not mix no load and full load readings. Use line voltage for three phase checks. Select the correct phase option when estimating load current. Keep units consistent. Enter zero only when a value is unknown.
The result is an engineering estimate. Real devices have losses, magnetizing current, impedance, saturation, temperature effects, and accuracy class limits. For protection work, always compare with manufacturer data and local electrical rules. Use the exports for records, field notes, and review sheets.
When measurements disagree, inspect polarity, clamp position, tap setting, meter range, and secondary wiring. Small entry errors can create large ratio changes. Repeat critical readings and record ambient conditions before final design approval decisions.