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Chapter 2
2) Inverter output terminals (U, V, and W)
- Use a cable thicker than the specified applicable cable for the wiring of output terminals to prevent the output
voltage between the inverter and motor dropping. Especially at low frequency output, a voltage drop due to
cable will cause the motor torque to decrease.
- Do not connect a phase-advanced capacitor or surge absorber on the output side of the inverter. If connected,
the inverter may trip or the phase-advanced capacitor or surge absorber may be damaged.
- If the cable length between the inverter and motor exceeds 20 m (especially in the case of 400 V class models),
the stray capacitance and inductance of the cable may cause a surge voltage at motor terminals, resulting in a
motor burnout. A special filter to suppress the surge voltage is available. If you need this filter, contact your
supplier or local Hitachi Distributor.
- When connecting multiple motors to the inverter, connect a thermal relay to the inverter output circuit for each
motor.
- The RC rating of the thermal relay must be 1.1 times as high as the rated current of the motor. The thermal relay
may go off too early, depending on the cable length. If this occurs, connect an AC reactor to the output of the
inverter.
3) DC reactor connection terminals (PD and P)
- Use these terminals to connect the optional DC power factor reactor (DCL). As the factory setting, terminals P
and PD are connected by a jumper. Remove this to connect the DCL.
- The cable length between the inverter and DCL must be 5 m or less.
Remove the jumper only when connecting the DCL. If the jumper is removed and the DCL is not
connected, power is not supplied to the main circuit of the inverter, and the inverter cannot operate.
4) External braking resistor connection terminals (P and RB) and regenerative braking unit connection terminals
(P and N)
- Inverter models with 22 kW or less capacity have a built-in regenerative braking (BRD) circuit. If you need
increased braking performance, connect an optional external braking resistor to terminals P and RB. Do not
connect an external braking resistor with resistance less than the specified value. Such a resistor may cause
damage to the regenerative braking (BRD) circuit.
- Inverter models with capacity of 30 kW or more do not have a built-in regenerative braking (BRD) circuit.
Increasing the braking performance of these models requires an optional regenerative braking unit and an
external braking resistor. Connect the P and N terminals of the optional regenerative braking unit to the P and N
terminals of the inverters.
- The cable length between the inverter and optional regenerative braking unit must be 5 m or less, and the two
cables must be twisted for wiring.
- Do not use these terminals for connecting any devices other than the optional external braking resistor and
regenerative braking unit.
5) Inverter ground terminal (G
- Be sure to ground the inverter and motor to prevent electric shock.
- According to the Electric Apparatus Engineering Regulations, connect 200 V class models to grounding
electrodes constructed in compliance with type-D grounding (conventional type-III grounding with ground
resistance of 100Ω or less) or the 400 V class models to grounding electrodes constructed in compliance with
type-C grounding (conventional special type-III grounding with ground resistance of 10Ω or less).
- Use a grounding cable thicker than the specified applicable cable, and make the ground wiring as short as
possible.
- When grounding multiple inverters, avoid a multi-drop connection of the grounding route and formation of a
ground loop, otherwise the inverter may malfunction.
Inverter
Inverter
Inverter
)
Inverter
Inverter
Inverter
2-12
Installation and Wiring
Grounding bolt
prepared by user
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