Connection Of The Brake Unit (Fr-Bu2) - Mitsubishi Electric FR-E720-008 Instruction Manual

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
MCCB
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. Even
when the wiring is twisted, the cable length must not exceed 10m.
∗4
It is recommended to install an external thermal relay to prevent overheat of discharging resistors.
∗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 GRZG 200-10Ω (three in series)
FR-BU2-7.5K
FR-BU2-15K
FR-BU2-H7.5K
FR-BU2-H15K GRZG 300-5Ω (eight in series)
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.
MC
R/L1
S/L2
T/L3
Inverter
Discharging Resistor
GZG 300W-50Ω (one)
GRZG 300-5Ω (four in series)
GRZG 400-2Ω (six in series)
GRZG 200-10Ω (six in series)
Connection of stand-alone option unit
∗2
T
MC
OCR
Motor
U
External
IM
V
thermal
∗4
relay
W
∗3
PR
P/+
P/+
∗1
N/-
N/-
BUE
∗3 ∗3 SD
5m or less
(16.4feet or less)
Recommended External
Thermal Relay
TH-N20CXHZ 1.3A
TH-N20CXHZ 3.6A
TH-N20CXHZ 6.6A
TH-N20CXHZ 11A
TH-N20CXHZ 3.6A
TH-N20CXHZ 6.6A
OCR
ON OFF
MC
GRZG type
discharging
∗5
resistor
R R
FR-BU2
A
∗1
B
C
1/L 5/L
1 3
TH-N20
2/T 6/T
1 3
To a resistor
To the brake unit
terminal P/+
2
37