Mitsubishi Electronics FR-V540-1.5K to 55K ユーザーズマニュアル

16

z Use the dedicated earth (ground) terminal to earth (ground) the inverter. (Do not use the screw in the case, 

chassis, etc.)

 

Use a tinned crimping terminal which does not contain zinc to connect the earth (ground) cable. Tighten the 

screw, taking care not to break its threads.

z Use the largest possible gauge for the earth (ground) cable. The gauge should be equal to or larger than those 

indicated in the following table. The earthing (grounding) point should be as near as possible to the inverter to 

minimize the earth (ground) cable length.

(Unit: mm

2

)

For use as a Low Voltage Directive-compliant product, use the PVC cables indicated in the parentheses for earthing 

(grounding).

z Earth (Ground) the motor on the inverter side using one wire of the 4-core cable.
z Always earth (ground) the motor and inverter.

(1)Purpose of earthing (grounding)

 

Generally, an electrical apparatus has an earth (ground) terminal, which must be connected to the ground 

before use.

 

An electrical circuit is usually insulated by an insulating material and encased. However, it is impossible to 

manufacture an insulating material that can shut off a leakage current completely, and actually, a slight current 

flow into the case. The purpose of earthing (grounding) the case of an electrical apparatus is to prevent 

operator from getting an electric shock from this leakage current when touching it.

 

To avoid the influence of external noises, this earthing (grounding) is important to audio equipment, sensors, 

computers and other apparatuses that handle low-level signals or operate very fast.

(2)Earthing (Grounding) methods and earthing (grounding) work

 

As described previously, earthing (grounding) is roughly classified into an electrical shock prevention type and 

a noise-affected malfunction prevention type. Therefore, these two types should be discriminated clearly, and 

the following work must be done to prevent the leakage current having the inverter's high frequency 

components from entering the malfunction prevention type earthing (grounding):

(a) Where possible, use independent earthing (grounding) for the inverter.

 

If independent earthing (grounding) (I) is impossible, use joint earthing (grounding) (II) where the inverter is 

connected with the other equipment at an earthing (grounding) point. Joint earthing (grounding) as in (III) 

must be avoided as the inverter is connected with the other equipment by a common earth (ground) cable.

 

Also a leakage current including many high frequency components flows in the earth (ground) cables of the 

inverter and inverter-driven motor. Therefore, they must use the independent earthing (grounding) method 

and be separated from the earthing (grounding) of equipment sensitive to the aforementioned noises.

 

In a tall building, it will be a good policy to use the noise malfunction prevention type earthing (grounding)

with steel frames and carry out electric shock prevention type earthing (grounding) in the independent 

earthing (grounding) method.

(b) Earthing (Grounding) must conform to the requirements of national and local safety regulations and 

electrical codes. 

 

(NEC section 250, IEC 536 class 1 and other applicable standards).

(c) Use the thickest possible earth (ground) cable. The earth (ground) cable should be of not less than the size 

indicated in the above table.

(d) The earthing (grounding) point should be as near as possible to the inverter to minimize the earth (ground)

cable length.

(e) Run the earth (ground) cable as far away as possible from the I/O wiring of equipment sensitive to noises 

and run them in parallel in the minimum distance.

(f) Use one wire in a 4-core cable with the earth (ground) terminal of the motor and earth (ground) it on the 

inverter side.

2.2kW or less

2 (2.5)

2 (2.5)

3.7kW

3.5 (4)

2 (2.5)

5.5kW, 7.5kW

5.5 (6)

3.5 (4)

11kW, 15kW

14 (16)

8 (10)

18.5kW to 37kW

22 (25)

14 (16)

45kW, 55kW

38 (35)

22 (25)

(I) Independent earthing (grounding) ... Best

(II) Joint earthing (grounding) ... Good

(III) Joint earthing (grounding) ... Not allowed

Inverter

Other
equipment

200V class
class D earthing (grounding)
400V class
class C earthing (grounding)

Inverter

Other
equipment

200V class
class D earthing (grounding)
400V class
class C earthing (grounding)

Inverter

Other
equipment

200V class
class D earthing (grounding)
400V class
class C earthing (grounding)