Connection Of The Brake Unit (Fr-Bu2) - Mitsubishi Electric FR-D720-008 Instruction Manual

Connection of stand-alone option unit
2.4.2

Connection of the brake unit (FR-BU2)

Connect the brake unit (FR-BU2(-H)) as shown below to improve the braking capability at deceleration. If the transistors in the
brake unit should become faulty, the resistor can be unusually hot. To prevent unusual overheat and fire, install a magnetic
contactor on the inverter's input side to configure a circuit so that a current is shut off in case of fault.
(1) Connection example with the GRZG type discharging resistor
Three-phase AC
power supply
∗1
Connect the inverter terminals (P/+ and N/-) and brake unit (FR-BU2) terminals so that their terminal names match
with each other.
(Incorrect connection will damage the inverter and brake unit.)
∗2
When the power supply is 400V class, install a step-down transformer.
∗3
The wiring distance between the inverter, brake unit (FR-BU2) and discharging resistor should be within 5m(16.4feet)
each. Even when the wiring is twisted, the cable length must not exceed 10m(32.8feet).
∗4
It is recommended to install an external thermal relay to prevent overheat of discharging resistor.
∗5
Refer to FR-BU2 manual for connection method of discharging resistor.
<Recommended external thermal relay>
Brake Unit
FR-BU2-1.5K
FR-BU2-3.7K
FR-BU2-7.5K
FR-BU2-15K
FR-BU2-H7.5K
FR-BU2-H15K
NOTE
Set "1" in Pr. 0 Brake mode selection of the FR-BU2 to use GRZG type discharging resistor.
Do not remove a jumper across terminal P/+ and P1 except when connecting a DC reactor.
32
MC
MCCB
Discharging Resistor
GZG 300W-50Ω (one)
GRZG 200-10Ω (three in series)
GRZG 300-5Ω (four in series)
GRZG 400-2Ω (six in series)
GRZG 200-10Ω (six in series)
GRZG 300-5Ω (eight in series)
∗2
T
MC
Motor
U
R/L1
IM
S/L2 V
W
T/L3
∗3
Inverter
P/+
∗1
N/-
∗3 ∗3
5m or less
(16.4feet or less)
Recommended External
ON OFF
MC
GRZG type
∗5
discharging resistor
R R
∗4
FR-BU2
PR
A
P/+ B
∗1
N/- C
BUE
SD
Thermal Relay
TH-N20CXHZ 1.3A
TH-N20CXHZ 3.6A
TH-N20CXHZ 6.6A
TH-N20CXHZ 1.1A
TH-N20CXHZ 3.6A
TH-N20CXHZ 6.6A