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Connection of stand-alone option unit
2
WIRING
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
<Recommended external thermal relay>
∗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.
Brake Unit Discharging Resistor
Recommended External
Thermal Relay
FR-BU2-1.5K GZG 300W-50Ω (one) TH-N20CXHZ 1.3A
FR-BU2-3.7K GRZG 200-10Ω (three in series) TH-N20CXHZ 3.6A
FR-BU2-7.5K GRZG 300-5Ω (four in series) TH-N20CXHZ 6.6A
FR-BU2-15K GRZG 400-2Ω (six in series) TH-N20CXHZ 11A
FR-BU2-H7.5K GRZG 200-10Ω (six in series) TH-N20CXHZ 3.6A
FR-BU2-H15K GRZG 300-5Ω (eight in series) TH-N20CXHZ 6.6A
NOTE
Set "1" in Pr. 0 Brake mode selection of the FR-BU2 to use GRZG type discharging resistor.
Do not remove the jumper across terminals P/+ and P1 except when connecting a DC reactor.
U
V
W
P/+
N/-
R/L1
S/L2
T/L3
Motor
IM
PR
N/-
BUE
SD
P/+
A
B
C
FR-BU2
OFFON
MC
Three-phase AC
power supply
MCCB
MC
Inverter
5m or less
T
MC
OCR
OCR
External
thermal
relay
GRZG type
discharging
resistor
RR
∗1
∗3
∗4
∗3
∗2
∗1
∗3
∗5
To the brake unit
terminal P/+
To a resisto
r
TH-N20
1/L1 5/L3
2/T1 6/T3