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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) 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 drive unit's input side to configure a circuit so that a current is shut off in case of fault.
<Recommended external thermal relay>
∗1 Connect the drive unit terminals (P/+ and N/-) and brake unit (FR-BU2) terminals so that their terminal names match with each other.
(Incorrect connection will damage the drive unit and brake unit.)
∗2 The wiring distance between the drive unit, brake unit (FR-BU2) and discharging resistor should be within 5m.
Even when the wiring is twisted, the cable length must not exceed 10m.
∗3 It is recommended to install an external thermal relay to prevent overheat of discharging resistor.
∗4 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
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
M
PR
N/-
BUE
SD
P/+
A
B
C
FR-BU2
GRZG type
discharging resistor
RR
MC
OFFON
MC
Three-phase AC
power supply
MCCB
MC
Drive unit
5m or less
OCR contact
OCR
External thermal
relay
∗1
∗2
∗3
∗1
∗2
∗4
To the drive
unit terminal P/+
To a resisto
TH-N20
1/L1 5/L3
2/T1 6/T3
