Hitachi SJ700B SERIES, Instruction Manual

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Chapter 2 Installation and Wiring
2 - 12
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 30 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 37 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 400 V class models to
grounding electrodes constructed in compliance with type-C grounding (conventional special
type-III grounding with ground resistance of 10
Ω 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
Grounding bolt
prepared by user
Inverter
Inverter
Inverter