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Harmonic Correction Unit
Eaton’s active harmonic filters, known as Harmonic Correction Units provide dynamic harmonic mitigation and power factor correction by actively injecting reactive currents into an electrical distribution system to cancel damaging harmonic currents and supporting power factor requirements at the point of connection.
Harmonic correction unit specifications
HCUn series
| Power electronics | 3-level IGBT |
| Control topology | Digital harmonic FFT Digital instantaneous reactive power |
| Efficiency and losses | 208 Vac ≥ 95% Three-phase compensation: ≤ 17.7 W/A Three-phase + N compensation: ≤ 19.7 W/A 380–415 Vac ≥ 97% Three-phase compensation: ≤ 20.4 W/A Three-phase + N compensation: ≤ 22.6 W/A |
| Current transformer | Any ratio with 1 A or 5 A secondary; Class 1.0 accuracy; 50/60 or 400 Hz rated (instrument rated or better); Grounded; can be shared with other devices |
| CT VA loading | 1 A: 0.04 VA 5 A: 1 VA |
| Quantity of CT | Two or three CTs for three-phase loads; three CTs are required for four-wire with neutral connected loads CT position (Grid or load sense) |
| Control basis | Closed or open loop |
| Modes or Operation | Multi-modes simultaneously or discrete |
| Spectrum cancellation and selection | 2nd to 51st harmonic order; discrete, fully selectable adjustable per harmonic order (amplitude % and ON/OFF) Phase harmonic correction Neutral harmonic correction with user-adjustable current limit up to three times unit rating Power factor correction (cos) Mains current load balancing |
| Operational features | % THDi setpoint, % THDv setpoint, Target PF setpoint |
| Harmonic attenuation and filtering performance | THDi < 3% in closed loop control; maximum 20:1 THDi (typical reduction with load harmonic above 50% unit rating) requires 3% or higher inductive impedance per nonlinear load |
| Mains current load balancing | Negative and zero sequence; selectable individually or simultaneously |
| Power factor correction | Optimize PF and target PF (cos) programmable leading (capacitive) or lagging (inductive) |
| Resonance avoidance | Output at specific harmonic order turned off if resonance or lack of impedance detected or manually turned off |
HCU2 series
| Standard rms output current ratings | 380 Vac to 480 Vac: 60 A, 120 A, 200 A, 300 A
600 Vac: 47 A, 94 A, 157 A, 235 A 690 Vac: 40 A, 80 A, 133 A, 200 A |
| Nominal frequency | 50/60 Hz, +/- 3 Hz auto sensing |
| Number of phases | 3-phase |
| Topology | Digital harmonic FFT
Digital reactive power |
| Losses | to 480 Vac <3%
to 690 Vac <5% |
| CT VA loading | 1.0 VA (5 A CT secondary) |
| Spectrum cancellation | 2nd to 51st, discrete; fully selectable per harmonic order (amplitude and on/off) |
| Control basis | Closed loop (for new installations)
Open loop compatible for retrofit applications |
| Harmonic attenuation | Closed loop: <3% THD(i); max 20:1 THD)i) reduction with load harmonic current above 50% of HCU2 rating
Open loop: <5% TDD Required 3% or higher inductive impedance per nonlinear load |
| Harmonic operational features | % THDi set point
% THDv set point |
| Harmonic avoidance | Output at specific harmonic order turned off if resonance or lack-of impedance detected; or manually turned off |
| Parallal operation | Up to 10 units per set of CT (to 51st order), any size combination
Backward compatibility with Eaton HCUE operated in parallel Contact Eaton for applications of more than 10 units |
| Parallel operation options | Master/master
Master/slave Multi-master/multi-slave Same as Eaton HCUE for retrofits |
| Parallel sequence options | Lead/lag with unit rotation: one unit operates to full capacity before next unit turns on; times rotation
Load share: all operating units function at the same output percentage |
| Parallel HMI control | Any unit permits viewing and changing parameter settings of complete system or any other unit in parallel system |
| Parallel communications | Proprietary COM bus between operating units |
| Power factor correction | Optimized unity PF, leading (capacitive) or lagging (inductive) power factor (Cos f) to target |
| Control response time | 25 µs |
| Harmonic correction time | 2 cycles |
| Reactive correction time | 1/4 cycle |
| Display | 144 mm QVGA TFT 64k-color touchscreen |
| Display parameters | Hundreds of parameters are available. Examples include: THDi, THDv, oscilloscope for viewing many selected parameters, phasor diagrams, load power, measured currents for Ih, Is, If, I neg seq, PF (Cos f), injected currents for Ih, I reactive, I neg seq, etc. |
| Communications capability | Modbus RTU, Modbus TCP/IP |
| Discrete input/outputs | 4 input and 4 output dry contracts; assignable |
| Noise level (ISO3746) | <70 dB at 1 meter from unit surface |
| Earthing (grounding) systems | EMC filter ground switch for Isolated Terra, high resistance ground or corner grounded systems |
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