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Connection of stand-alone option units
2.5 Connection of stand-alone option units
The inverter accepts a variety of stand-alone option units as required.
Incorrect connection will cause inverter damage or accident. Connect and operate the option unit carefully in
accordance with the corresponding option unit manual.
2.5.1 Connection of the brake unit (FR-BU2)
Connect the brake unit (FR-BU2) as shown below to improve the braking capability at deceleration.
(1) Connection example with the GRZG type discharging resistor
<Recommended external thermal relay>
*1 Connect the inverter terminals (P/+, 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 Keep a wiring distance of within 5m between the inverter, brake unit (FR-BU2) and discharging resistor. Even when the wiring
is twisted, the cable length must not exceed 10m. When twisting, twist at least 5 times per meter.
The brake unit may be damaged if cables are not twisted when the wiring length is 5m or more or the wiring length exceeds
10m or more even if cables are twisted.
*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
FR-BU2-H30K
GRZG 400-2Ω (twelve in series)
TH-N20CXHZ 11A
CAUTION
⋅ 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.
U
V
W
P/+
N/-
R/L1
S/L2
T/L3
Motor
M
Inverter
PR
N/-
BUE
SD
P/+
A
B
C
FR-BU2
GRZG type
discharging resistor
External thermal
relay
RR
Three-phase AC
power supply
MCCB
MC
OFFON
MC
T
*1
*3
*3
*2
MC
*4
*5
OCR contact
OCR
10m or less
To the brake
unit terminal P/+
To a resisto
r
TH-N20
1/L1 5/L3
2/T1 6/T3