Mitsubishi Electric FR-D720S SC EC Instruction Manual page 72

Connection of stand-alone option units
It is recommended to configure a sequence, which shuts off power in the input side of the in-
verter by the external thermal relay as shown below, to prevent overheat and burnout of the high
duty brake resistor in case the regenerative brake transistor is damaged. The following figure
shows two connection examples (circuits). (The brake resistor can not be connected to the
FR-D720S-008SC or 014SC.)
Example 1
Power
supply
Fig. 3-27: Protection circuits
Refer to Tab. 3-19 for the type number of each capacity of thermal relay and the diagram for
the connection.
When the power supply is 400V class, install a step-down transformer.
Power Supply
Voltage
230V
400V
Tab. 3-19: Resistor and thermal relay combination
To the inverter
P/+ terminal
b
CAUTION:
● The brake resistor connected should only be the dedicated brake resistor.
● Perform wiring and operation according to the Instruction Manual of each option
unit.
● Brake resistor can not be used with the brake unit (FR-BU2), high power factor
converter (FR-HC), power supply regeneration converter (FR-CV), etc.
● Do not connect a resistor directly to the DC terminals P/+ and N/–. This could cause
a fire.
3 - 36
Inverter Thermo relay
(OCR)
T
ON OFF
OCR
contact
High-duty Brake
Type
Resistor
FR-ABR-0.4K
FR-ABR-0.75K
FR-ABR-1.5K
FR-ABR-H0.4K
FR-ABR-H0.75K
FR-ABR-H1.5K
FR-ABR-H2.2K
FR-ABR-H3.7K
FR-ABR-H5.5K
FR-ABR-H7.5K
Example 2
Brake
restistor
Power
supply
Thermal Relay Type
(Mitsubishi Product)
TH-N20CXHZKP-0.7A
TH-N20CXHZKP-1.3A
TH-N20CXHZKP-2.1A
TH-N20CXHZKP-0.24A
TH-N20CXHZKP-0.35A
TH-N20CXHZKP-0.9A
TH-N20CXHZKP-1.3A
TH-N20CXHZKP-2.1A
TH-N20CXHZKP-2.5A
TH-N20CXHZKP-3.6A
Fig. 3-28:
Connecting the thermal relay
To a resistor
Inverter
Thermo relay
(OCR)
T
ON OFF
OCR
contact
Contact Rating
110V AC/5A
220V AC/2A (AC 11 class),
110V DC/0.5A
220V DC/0.25A (DC 11 class)
Wiring
Brake
restistor
I002043E
I001458E