Hitachi Sj7002 Owners Manual

Introduction
Motor ControlAccessories
5–2
Introduction
A motor speed control system will obviously incl ude a motor and inverter, as well as fuses for 
safety. If you are connecting a motor to the inverter  on a test bench just to get started, that’s all 
you may need for now. But a fully developed sy stem can also have a variety of additional 
components. Some can be for noise suppressi on, while others may enhance the inverter’s 
braking performance.  The figure below shows a  system with several...

SJ7002 Inverter
Motor ControlAccessories
5–3
Component Descriptions
AC Reactors, 
Input SideThis is useful in suppressing  harmonics induced on the power su pply lines, or when the main 
power voltage imbalance exceeds 3% (and power s ource capacity is more than 500 kVA), or to 
smooth out line fluctu ations. It also improves the power factor.
In the following cases for a general-purpose inve rter, a large peak current flows on the main 
power supply side, and is able  to destroy the inverter module:
 If...

Component Descriptions
Motor ControlAccessories
5–4
Zero-phase 
Reactor (RF 
Noise Filter)Electrical noise interference may occur 
on nearby equipment such as a radio 
receiver. The zero-phase reactor helps 
reduce radiated noise from the inverter 
wiring. It can be used on the input or 
output side of the inverter. The example 
zero-phase reactor shown to the right 
comes with a mounting bracket. The 
wiring must go through the opening to 
reduce the RF component of the electri-
cal noise. Loop the...

SJ7002 Inverter
Motor ControlAccessories
5–5
Expansion CardsThe SJ–FB Encoder Feedback Board installs in 
the inverter’s expansion bay, which can accept 
up to two expansion cards. The encoder card 
accepts two-channel incremental encoder 
signals. Position feedback is essential for certain 
torque-control algorithms, and is useful for 
improving low-speed performance. The card can 
also generate linear  acceleration/deceleration 
ramps for velocity control.
All wiring associated with this card connects...

Dynamic Braking
Motor ControlAccessories
5–6
Dynamic Braking
IntroductionThe purpose of dynamic braking is to improve the ability of the inverter 
to stop (decelerate) the motor and load. This becomes necessary when an 
application has some or all of  the following characteristics:
 High load inertia compared to the available motor torque
 The application requi res frequent or sudden changes in speed
 System losses are not great enough to slow the motor as needed
When the inverter reduces its output...

SJ7002 Inverter
Motor ControlAccessories
5–7
Dynamic Braking 
Selection TablesThe SJ7002 Series 200V and 400V class inverter models  in the 1/2 to 30 HP range have internal 
braking units. Additional stopping torque is avai lable by adding external resistors. The required 
braking torque depends on your part icular application. Other tables in this section will help you 
choose the prop er resistor.
NOTE: For inverters larger than 30 HP (22kW), an  external braking unit will be required. 
Contact your...

Phone: 800.894.0412   

Troubleshooting 
and Maintenance
In This Chapter....page
— Troubleshooting................................................................................   2
— Monitoring Trip Events, History, & Conditions...................................   5
— Restoring Factory Default Settings.................................................   16
— Maintenance and Inspection...........................................................   17
—...

Troubleshooting
Troubleshooting
and Maintenance
6–2
Troubleshooting
Safety MessagesPlease read the following safety messages be fore troubleshooting or performing maintenance 
on the inverter and motor system.
WARNING:  Wait at least ten (10) minutes after turning OFF the input power supply before 
performing mainte nance or an inspection. Otherwise, th ere is the danger of electric shock.
WARNING: Make sure that only qualified personnel  will perform maintenance, inspection, 
and part replacement....

SJ7002 Inverter
Troubleshooting
and Maintenance
6–3
Troubleshooting 
TipsThe table below lists typical symptoms  and the corresponding solution(s). 
Symptom/conditionProbable CauseSolution
The motor 
will not run. The inverter 
outputs U, V, W 
are not supplying  voltage. •
Is the frequency command source 
A001 parameter setting correct?
• Is the Run command source A002 
parameter setting correct? •
Make sure the parameter setting 
A001 is correct.
• Make sure the parameter setting 
A002 is correct.
• Is...