CIRCUTOR LCL User Manual

LCL FILTERS

INSTRUCTIONS MANUAL

(M98121701-03-09A)

(c)

CIRCUTOR S.A.

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2

TABLE OF CONTENTS

TABLE OF CONTENTS 2
1 CHECKS ON RECEIPT OF THE EQUIPMENT. 3
2 INTRODUCTION. 3
3 OPERATING PRINCIPLE. 3

3.1 HOW TO SELECT A LCL FILTER? 3

4 TECHNICAL CHARACTERISTICS 4

4.1 GENERAL. 4

4.2 REACTORS 4

4.3 CAPACITORS 4

4.4 STANDARD TYPES ( THREE PHASE 50HZ ) 5

4.5 OVERCOMPENSATION RELAY OPTION 5

4.6 DIMENSIONS AND WEIGHT 6

4.7 SCHEMATICS 8

5 INSTALLATION AND START-UP. 9

5.1 LOCATION. 9

5.2 INITIAL CHECKS (PRE-INSTALLATION, SWITCH THE POWER OFF). 9

5.3 CONNECTING THE POWER CIRCUIT. (SEE SCHEMATICS IN FIG 3) 9

5.4 CONNECTING THE OPERATING CIRCUIT (ONLY IN CASE OF OVERCOMPENSATION PROTECTION) 9

5.5 START UP. 9

6 CHECK POINTS. 9
7 PERIODICAL SERVICING. 10
8 SAFETY. 10
9 TECHNICAL SERVICE AND GUARANTEE. 10

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3

M

3

LCL FILTER

MAINS

IMPEDANCE

CONVERTER

L1 L2

L3

C

L4

1 CHECKS ON RECEIPT OF THE EQUIPMENT.

Before installing and handling the equipment check that:

1) The equipment has not been damaged during delivery.

2) The equipment supplied is suitable for your requirements and is the type you ordered.

3) The operating voltage of the equipment supplied is suitable for your requirements.

4) Manuals for the equipment and for the regulator are supplied with the capacitor bank.

5) If any problem is noticed, please contact the commercial service department of CIRCUTOR S.A.

2 INTRODUCTION.

LCL filters are specially designed to reduce harmonics of current absorbed by power converters, with
a rectifier input stage. (Frequency converters for motors, UPS, etc.). Mainly, they are made of a
parallel-series combination of reactors and capacitors adapted to reduce the THD(I) of rectifiers. They

are specially designed to reduce the THD(I) to values of approximately 8%, in order to comply with

IEC-61000-3.4 and IEEE-519 standards.

3 OPERATING PRINCIPLE.

The structure of LCL filters is as shown in the schematics below. The basic filter is designed with
L1,L2, L3 and C. In some cases reactor L4, is already placed in front of the converter. In such case L2
may be unnecessary

Fig. 1.- LCL filters Structure

3.1 How to select a LCL filter?

LCL filters must be selected according to the current absorbed by the converter. In case of converters
with very low power rating, a unique LCL filter may be used to supply several converters, but only in
case the all start and stop at the same time. If several converters starting and stopping separately are
supplied by the same LCL filter, the system is not effective on filtering the harmonics. In such case an
individual LCL should be used for each converter.

ATTENTION: LCL filters may produce cos overcompensation in case that the converter is absorbing
a current much lower than the rated current of the filter itself. This can be avoided by disconnecting
the parallel LC circuit when the current falls below a certain adjustable limit. An optional protection
circuit, consisting of a CMM-96-MD and a contactor, may be added to perform this function, if
requested in the order.