User Manual
EM303B General Purpose Inverter
26
EM303B-0R7~015
Braking Resistor
(Optional)
PB
M
U
V
W
T
S
R
EM303B-018~400
Braking Resistor(
Optional
)
Braking Unit(
Optional
)
M
U
V
W
T
S
R
Figure 3-4 Standard Wiring of Main Circuit
3.2.5
Wiring Main Circuit on Input Side
Installing a Circuit Breaker
Always install an air circuit breaker (MCCB) between the power supply and input terminals.
Choose a MCCB with a capacity of 1.5-2 times of the inverter’s rated current.
The time characteristics of MCCB should meet that of inverter’s overheating protection
(150% of rated current /1 minute).
If single MCCB is shared by two or more inverters or other devices, the contact of fault
output relay shall be connected to power contactor coil, so that the power supply will be
turned off by the fault signals, as shown in Figure 3-5.
Fault Relay
Contact
EC
EB
MC
OFF
MC
ON
MCCB
T
S
R
EM303B
Figure 3-5 Connecting to Input Circuit Breaker
Installing a Leakage Circuit Breaker
High frequency leakage current is generated by high frequency PWM signal output of
inverter. Select a special purpose leakage breaker with a trigger current≥30mA. For a regular
leakage breaker, the trigger current≥200mA and the active time at 0.1S or above.
Installing an Electromagnetic Contactor
Install an electromagnetic contactor which is applicable to inverter as shown in Figure 3-5.
