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3.3.2
Cables and wiring length
(1) Cable size and other specifications of the main circuit terminals and the earthing terminal
Select the recommended cable size to ensure that a voltage drop will be 2% or less.
If the wiring distance is long between the inverter and motor, a main circuit cable voltage drop will cause the motor torque to
decrease especially at the output of a low frequency.
The following table indicates a selection example for the wiring length of 20m.
Three-phase 400V class (when input power supply is 440V)
Applicable Inverter
Model
FR-D740-012(SC) to 080(SC)
FR-D740-120(SC)
FR-D740-160(SC)
Single-phase 200V class (when input power supply is 220V)
Applicable Inverter
Model
FR-D720S-008(SC) to 042(SC)
FR-D720S-070(SC)
FR-D720S-100(SC)
The cable size is that of the cable (HIV cable (600V class 2 vinyl-insulated cable) etc.) with continuous maximum permissible temperature of 75°C. Assumes
that the surrounding air temperature is 50°C or less and the wiring distance is 20m or less.
The recommended cable size is that of the cable (THHW cable) with continuous maximum permissible temperature of 75°C. Assumes that the surrounding
air temperature is 40°C or less and the wiring distance is 20m or less.
(For the use in the United States or Canada, refer to page 23.)
The recommended cable size is that of the cable (PVC cable) with continuous maximum permissible temperature of 70°C. Assumes that the surrounding air
temperature is 40°C or less and the wiring distance is 20m or less.
(Selection example for use mainly in Europe.)
The terminal screw size indicates the terminal size for R/L1, S/L2, T/L3, U, V, W, PR, P/+, N/-, P1 and a screw for earthing (grounding).
(For single-phase power input, the terminal screw size indicates the size of terminal screw for L1, N, U, V, W, PR, +, -, P1 and a screw for earthing
(grounding).)
NOTE
Tighten the terminal screw to the specified torque. A screw that has been tighten too loosely can cause a short circuit or
malfunction. A screw that has been tighten too tightly can cause a short circuit or malfunction due to the unit breakage.
Use crimp terminals with insulation sleeve to wire the power supply and motor.
The line voltage drop can be calculated by the following formula:
3
Line voltage drop [V] =
Use a larger diameter cable when the wiring distance is long or when it is desired to decrease the voltage drop (torque
reduction) in the low speed range.
Crimp
Terminal
Tightening
Terminal
Screw
Torque
R/L1
Size
N·m
S/L2
U, V, W
T/L3
M4
1.5
2-4
M4
1.5
5.5-4
M4
1.5
5.5-4
Crimp
Terminal
Tightening
Terminal
Screw
Torque
Size
N·m
L1, N U, V, W L1, N U, V, W
M3.5
1.2
2-3.5
M4
1.5
2-4
M4
1.5
5.5-4
wire resistance [mΩ/m]
×
×
1000
HIV Cables, etc. (mm
R/L1
Earthing
S/L2
U, V, W
(ground)
T/L3
cable
2-4
2
2
2-4
3.5
2
3.5
5.5-4
3.5
3.5
3.5
HIV Cables, etc. (mm
Earthing
(ground)
cable
2-3.5
2
2
2-4
2
2
2-4
3.5
2
3.5
wiring distance [m]
current [A]
×
Cable Size
2
AWG
)
PVC Cables, etc. (mm
R/L1
R/L1
S/L2
U, V, W
S/L2
T/L3
T/L3
2
14
14
2.5
12
14
4
12
12
4
Cable Size
2
AWG
)
PVC Cables, etc. (mm
L1, N U, V, W L1, N U, V, W
2
14
14
2.5
2
14
14
2.5
12
14
4
WIRING
2
)
Earthing
U, V, W
(ground)
cable
2.5
2.5
2.5
4
4
4
2
)
Earthing
(ground)
cable
2.5
2.5
2.5
2.5
2.5
4
7
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