Connection Of The Brake Unit (Fr-Bu2) - Mitsubishi Electric FR-A720-00030-NA Instruction Manual

2.5.2

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
Three-phase AC
power supply
*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 Be sure to remove the jumper across terminals PR and PX when using the FR-BU2 with the inverter of FR-A720-00330 (FR-
A740-00170) or lower.
*4 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 (32.8feet).
*5 It is recommended to install an external thermal relay to prevent overheat of discharging resistors.
*6 Refer to FR-BU2 manual for connection method of discharging resistor.
<Recommended external thermal relay>
Brake Unit Discharging Resistor
FR-BU2-1.5K GZG 300W-50 (one)
GRZG 200-10 (three in series)
FR-BU2-3.7K
GRZG 300-5 (four in series)
FR-BU2-7.5K
GRZG 400-2 (six in series)
FR-BU2-15K
FR-BU2-H7.5K GRZG 200-10 (six in series)
FR-BU2-H15K GRZG 300-5 (eight in series)
FR-BU2-H30K GRZG 400-2 (twelve in series)
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.
T
MC
MCCB
R/L1
S/L2
T/L3
Inverter
PR
*3
PX
Recommended External Thermal Relay
Connection of stand-alone option units
*2
GRZG type
discharging resistor
OCR
MC
R
External thermal
Motor
U
relay
*5
V
IM
W
FR-BU2
*4
PR
P/+
P/+
*1
N/- N/-
BUE
SD
*4
5m or less
(16.4 feet)
TH-N20CXHZ 1.3A
TH-N20CXHZ 3.6A
TH-N20CXHZ 6.6A
TH-N20CXHZ 11A
TH-N20CXHZ 3.6A
TH-N20CXHZ 6.6A
TH-N20CXHZ 11A
ON OFF
OCR contact
MC
*6
R
A
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
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