LC Complex Harmonic Filter

Model Number

LCF

Applications
Between inverter and motor

Applicable Loads
Motor and machinery operated by PWM inverter.

Applicable Locations
Manufactory, power plant, water treatment facility, Dam, etc 　

Benefits

Improve voltage and current waveform
The LCF convert the harsh PWM waveform back to near sinusoidal waveform. If the voltage waveform is converted to a sine wave, the issue of motor terminal over-voltage and dv/dt are removed. In motor side, normal motors are designed to operate on sine wave so motor performance can be improved and motor life can be expended. 　

Reduce motor peak voltage
The motor driven by PWM inverter can experience motor terminal peak voltage nearly twice the DC bus voltage. It means that motor terminal peak voltage could be 1700V volts(600V drive) or 1300V volts(480V drive).
This high peak voltage is experienced in low HP applications.
The LCF protect motors fro insulation breakdown due to voltage stress. 　

Reduce voltage reflection
If motor driven by PWM inverter has long motor cable, voltage amplification can be experienced. The severity of this condition is determined by motor surge impedance, cable surge impedance, and cable length.
The voltage reflection coefficient (R ) indicated what percentage of the incident voltage will be reflected and therefore added to the incident voltage at the motor terminals. 　

Reflection coefficient (R ) = (Zm-Zc)/(Zm+Zc)
Zm: Motor surge impedance, Zc: Cable surge impedance 　
Motor terminal peak voltage = (1 + R) times DC bus voltage

HP	R	Zm	Zc
25 HP	0.90	1500 ohms	80 ohms
50 HP	0.83	750 ohms	70 ohms
100 HP	0.76	375 ohms	50 ohms
200 HP	0.65	188 ohms	40 ohms
400 HP	0.52	94 ohms	30 ohms

Table 1. Typical reflection coefficient and surge impedance for various motor ratings 　 The LCF reduce the reflection coefficient by summing cable surge impedance
and reactor surge impedance of LCF. 　 Extend critical cable length The possible distance of voltage amplification is called the "Critical Cable Length" .
It is determined by two factors. One is the voltage rise time (dv/dt) and the other is the speed of electromagnetic pulse travel on the cable.
The speed normally 100 meters/microsecond. The voltage rise time can be defined as time for the voltage pulse to rise 10% to 90% of the DC bus voltage. 　

Critical Cable Length = (100 m/μ sec x voltage rise time (μ sec))/2

Voltage Rise Time	Critical Cable Length
6 μ sec	300 meters
1 μ sec	50 meters
0.5 μ sec	25 meters
0.1 μ sec	5 meters

The LCF expend the critical cable length of motor by reducing dv/dt to make slow voltage rise time. 　

Features & Options
Compact and easy-to-install. Quite operation and proper ventilation. Standardized up to 1000HP (based on load capacity) Special voltage available up to 6600V by request.

Selection Tables
Select L-C complex filter based on the horse-power (or kilowatt) rating of motor.

HP	kW	Rating	Dimension			Fig.
			W	D	H
3	2.3	LCF38003	350	500	500	1
5	3.8	LCF38005	350	500	500	1
10	7.5	LCF38010	350	500	500	1
20	15	LCF38020	500	800	1000	1
40	30	LCF38040	600	1000	1200	1
60	45	LCF38060	600	1200	1600	2
100	75	LCF38100	800	1400	1600	2
200	150	LCF38200	800	1500	1600	2
300	225	LCF38300	900	1500	2350	2
400	300	LCF38400	1100	1500	2350	2
600	450	LCF38600	1100	1500	2350	2
800	600	LCF38800	1300	1500	2350	2
1000	750	LCF381000	1500	1500	2350	2

Table 1. Selection Table of LCF (Rated voltage: 380V)

• 220V and 440V also available.
  
• Other rating of LCF is available by request.
  
• W = Width, D = Depth, H = Height
  
• All weight and dimensions are subject to change without notice.

Product Selection Guide

Step1. Find motor fed by PWM inverter
Find motor fed by PWM inverter to apply the LCF.

Step2. Get the motor information
Get the motor information such as rated voltage, horse-power (or kilowatt), power factor, and cable length and size etc.
Step3. Choose the rating of LCF at Table 1
Choose the proper rating of LCF at Table 1 based on the horse-power (or kilowatt). 　

Result of LCF