CT / Meter Multiplier
Compute the meter multiplier from CT primary/secondary current and PT ratio, then convert secondary current / meter reading to primary current and energy.
Key points
CT / Meter Multiplier: Compute the meter multiplier from CT primary/secondary current and PT ratio, then convert secondary current / meter reading to primary current and energy. Formula: K_CT = I₁/I₂ | multiplier = K_CT·K_PT | W₁ = W₂·multiplier. Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. The CT ratio is primary rated current divided by secondary rated current; multiply the meter reading by the combined multiplier (CT×PT) to get primary energy. Never open-circuit a CT secondary: it can generate dangerous high voltage. Short the secondary terminals before maintenance.
Inputs
K_CT = I₁/I₂ | multiplier = K_CT·K_PT | W₁ = W₂·multiplierCalculation model (updates with parameters)
| CT ratio K_CT | 40.0 : 1 | 200 A / 5 A |
| PT ratio K_PT | 1.000 : 1 | 低压直接计量为 1 |
| Meter multiplier | 40.00 × | K_CT × K_PT，Reading乘此Value即Primary电量 |
| Primary current (from I₂) | 120 A | I₂ × K_CT = 3 A × 40.0 |
| Primary energy W₁ | 4 MWh | 100.00 kWh × 40.00 |
| CT loading | 60.0 % | 建议 20~100% 额定Secondarycurrent |
| Secondary rated current | 5 A | 5A 或 1A 系统 |
| Primary rated current | 200 A | CT 铭牌Value |
Engineering notes
- The CT ratio is primary rated current divided by secondary rated current; multiply the meter reading by the combined multiplier (CT×PT) to get primary energy.
- Never open-circuit a CT secondary: it can generate dangerous high voltage. Short the secondary terminals before maintenance.
- CT error increases significantly below 20% rated load; for long-term light load, choose a smaller ratio or a 1 A secondary system.
FAQ
- What is CT / Meter Multiplier for?
- Compute the meter multiplier from CT primary/secondary current and PT ratio, then convert secondary current / meter reading to primary current and energy.
- What is the formula for CT / Meter Multiplier?
- Core formula: K_CT = I₁/I₂ | multiplier = K_CT·K_PT | W₁ = W₂·multiplier. The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using CT / Meter Multiplier?
- The CT ratio is primary rated current divided by secondary rated current; multiply the meter reading by the combined multiplier (CT×PT) to get primary energy. Never open-circuit a CT secondary: it can generate dangerous high voltage. Short the secondary terminals before maintenance. CT error increases significantly below 20% rated load; for long-term light load, choose a smaller ratio or a 1 A secondary system.