Hitachi Sj7002 Owners Manual

							Maintenance and Inspection
Troubleshooting
and Maintenance
6–24
To install the new fan(s):
1. Slide the fan(s) into the mounting locations in the mounting 
plate. To ensure the correct airflow, be sure that the label on 
each fan faces toward the vent openings (top of inverter).
2. Connect the fan wiring to terminals J21 or J22 (depending on 
the inverter model) on the main circuit board.
3. Put the mounting plate in position on the top of the inverter. 
Press downward on the fan units  until the retention tabs click 
into place.
4. Replace the upper and lower front panel covers on the inverter, 
using two (2) screws for each panel.
For inverters with sheet metal housings...
1. Loosen the screws that secure the  lower front panel. Remove the panel from the inverter.
2. Turn OFF power to the inverter and confirm that the Charge Indicator LED is OFF.
3. Loosen the two screws that secure the  upper front panel. Remove the panel from the 
inverter.
4. Remove the screws that secure the fan unit to the top of the inverter.
5. Lift the cooling fan unit away from the top of the inverter housing.
6. Remove the defective fan(s) from  the cooling fan mounting plate.
To install the new fan(s):
1. Slide the fan(s) into the mounting 
locations in the mounting plate. To 
ensure the correct airflow, be sure that 
the label on each fan faces toward the 
vent openings (top of inverter).
2. Connect the fan wiring to terminals J21, 
J22, or J23 (depending on the inverter 
model) on the main circuit board.
3. Put the mounting plate in position on 
the top of the inverter housing and 
secure it with screws.
4. Replace the upper a nd lower front panel covers on the inverter and secure them with screws.

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							SJ7002 Inverter
Troubleshooting
and Maintenance
6–25
General Inverter 
Electrical 
MeasurementsThe following table specifies how to measure key  system electrical parameters. The diagrams 
on the next page show inverter-motor systems  and the location of measurement points for these 
parameters.
Note 1: Use a meter indicating  a fundamental wave effective value for voltage, and meters 
indicating total effective va lues for current and power.
Note 2: The inverter output has a  distorted waveform, and harm onic frequencies may cause 
erroneous readings. However, the measuring instruments and methods listed above 
provide reasonably accurate results.
Note 3: A general-purpose digital volt meter (DVM ) is not usually suitable to measure a 
distorted waveform  (not pure sinusoid).
ParameterCircuit location
of measurementMeasuring 
instrumentNotesReference Value
Supply voltage E
1
ER – across L1 and L2
E
S – across L2 and L3
E
T – across L3 and L1 Moving-coil type 
voltmeter or recti-
fier type voltmeter
Fundamental 
wave effective 
valueCommercial supply 
voltage (200V class) 
200-240V, 50/60 Hz
400V class 380-
460V, 50/60 Hz
Supply current I
1
Ir – L1, Is – L2, It – L3 Moving-coil type  ammeter Total effective 
value —
Supply power W
1W11 – across L1 and L2
W
12 – across L2 and L3 Electronic type 
wattmeter
Total effective 
value —
Supply power  factor Pf
1
—
Output voltage  E
0
EU – across U and V
E
V – across V and W
E
W – across W and U Rectifier type 
voltmeter
Total effective 
value —
Output current I
oIU – U
I
V – V
I
W – W Moving-coil type 
ammeter
Total effective 
value —
Output power W
oW01 – across U and V
W
02 – across V and W Electronic type 
wattmeter
Total effective 
value —
Output power  factor Pf
o
Calculate the output power factor from the output voltage E, output 
current I, and output power W. —
Pf1
W1
3E1×
I1×
-----------------------------
-
100 %
×
=
Pf0
W0
3E0× I0×
-----------------------------
-
100 %
×
=

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							Maintenance and Inspection
Troubleshooting
and Maintenance
6–26
The figure below shows measurement locations fo r voltage, current, and power measurements 
listed in the table on the previous page. The voltage to be measured is the fundamental wave 
effective voltage. The power to be measured is the total effective power.
Inverter Output 
Voltage Measure-
ment TechniquesTaking voltage measurements around drives equi pment requires the right equipment and a safe 
approach. You are working with high voltages  and high-frequency switching waveforms that 
are not pure sinusoids. Digital voltmeters will  not usually produce reliable readings for these 
waveforms. And, it is usually  risky to connect high voltage signals to oscilloscopes. The 
inverter output semiconductors have some  leakage, and no-load measurements produce 
misleading results. So, we highl y recommend using the following circuits to measure voltage 
for performing the equipment inspections.
HIGH VOLTAGE:  Be careful not to touch wiring or connector terminals when working with 
the inverters and taking measurements. Be sure to  place the measurement circuitry above in an 
insulated housing before using them.
E1
I1I1
I1
I1
EU-V
EU-V
EU-V
W01
W02
W01
W02E1
E1
I2
I3
Three-phase measurement diagram
L1
L2
L3 Inverter
Motor
T1
T2
T3
R
S
T U
V
W
V/T2
W/T3 U/T1
L2/S
L3/T L1/R
V/T2
W/T3 U/T1
L2/S
L3/T L1/R
V class Diode bridge Voltmeter
200V class 600V 0.01A min. 300V range
400V class 1000V 0.1 A min. 600V range
220k Ω
2W
+–
220k Ω
2W
+–
Voltage measurement with  load
Inverter
Voltage measurement without load
Inverter
V class Diode bridge Voltmeter
200V class 600V 0.01A min. 300V range
400V class 1000V 0.1 A min. 600V range
5kΩ
30W

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							SJ7002 Inverter
Troubleshooting
and Maintenance
6–27
IGBT Test MethodThe following procedure will check the power mo dule, including inverter transistors (IGBTs), 
IPM, diodes, and thyrister unt il replacement of inverter (1,000,000 start/stop cycles):
1. Disconnect input power to te rminals [R, S, and T] and mo tor terminals [U, V, and W]. 
2. Disconnect any wires from  terminals [P] and [RB] for regenerative braking.
3. Use a Digital Volt Meter (DVM) and set it fo r 1 ohm resistance range. You can check the 
status of the charging state of terminals [R, S, T,  U, V, W, RB, P, and N] of the inverter and 
the probe of the DVM by m easuring the charging state.
Almost infinite ohms =  “non-conducting,” and 0 to  10 ohms = “conducting.”
NOTE: The resistance values for the diodes or the tr ansistors will not be exactly the same, but 
they will be close. If you find a signi ficance difference, a problem may exist.
NOTE: Before measuring the voltage  between [P] and [N] with the DC current range, confirm 
that the smoothing capacitor is discharged fully, then execute the tests.
Circuit TypeDVM  ProbeMeasured Value+–
Converter
D1R PD Non-conducting
PD R Conducting
D2S PD Non-conducting
PD S Conducting
D3T PD Non-conducting
PD T Conducting
D4R N Conducting
N R Non-conducting
D5S N Conducting
N S Non-conducting
D6T N Conducting
N T Non-conducting
Inverter
TR1U P Non-conducting P U Conducting
TR2V P Non-conductingP V Conducting
TR3W P Non-conducting P W Conducting
TR4U N Conducting
N U Non-conducting
TR5V N Conduct
N V Non-conducting
TR6W N ConductingN W Non-conducting
R
S
T
D1 D2 D3
D4 D5 D6
U
V
W
TR1 TR2 TR3
TR4 TR5 TR6
PDPRB
C
TR7
+
Converter
Inverter
N

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							Maintenance and Inspection
Troubleshooting
and Maintenance
6–28
Dynamic  Braking
(0.4kW–11kW)
TR7RB P Non-conducting
P RB Conducting
RB N Non-conducting
N RB Non-conducting
Circuit TypeDVM  ProbeMeasured Value+–

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							SJ7002 Inverter
Troubleshooting
and Maintenance
6–29
Warranty
Warranty Terms
The warranty period under normal installation and  handling conditions shall be two (2) 
years from the date of manufacture (“DATE” on product nameplate), or one (1) year 
from the date of installation, whichever occurs  first. The warranty shall cover the repair 
or replacement, at Hitachis sole discretion , of ONLY the inverter that was installed.
1. Service in the following cases, even within  the warranty period, shall be charged to 
the purchaser:
a. Malfunction or damage caused by mis-ope ration or modification or improper 
repair
b. Malfunction or damage caused by a dr op after purchase and transportation
c. Malfunction or damage caused by fire,  earthquake, flood, lightning, abnormal 
input voltage, contamination,  or other natural disasters
2. When service is required for the product at  your work site, all expenses associated 
with field repair shall be charged to the purchaser.
3. Always keep this manual handy; please do  not lose it. Please contact your Hitachi 
distributor to purchase replac ement or additional manuals.

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							Glossary and 
Bibliography
In This Appendix....page
— Glossary............................................................................................   2
— Bibliography......................................................................................   6
A

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							Glossary
Appendix A
A–2
Glossary
Ambient
Te m p e r a t u r eThe air temperature in the chamber containing a powered electronic unit. A unit’s heat sinks 
rely on a lower ambient temperature in order to dissipate heat away fro m sensitive electronics.
Arrival FrequencyThe arrival frequency refers to the set output frequency of the inverter for the constant speed 
setting. The arrival frequency feature turns ON  an output when the inverter reaches the set 
constant speed. The inverter ha s various arrival frequencies and pulsed or latched logic options.
Auto-tuningThe ability of a controller to execute a procedur e that interacts with a load to determine the 
proper coefficients to use in the control algo rithm. Auto-tuning is a common feature of process 
controllers with PID loops. Hitachi inverters feat ure auto-tuning to determine motor parameters 
for optimal commutation. Auto-tuning is avai lable as a special command from a digital 
operator panel. See also  digital operator panel.
Base FrequencyThe power input frequency for which an AC induction motor is designe d to operate. Most 
motors will specify a 50 to 60 Hz value. Th e Hitachi inverters have a programmable base 
frequency, so you must ensure  that parameter matches the attached motor. The term  base 
frequency  helps differentiate it from the carrier frequency. See also  carrier frequency and 
frequency setting .
Braking ResistorAn energy-absorbing resistor that dissipates en ergy from a decelerating load. Load inertia 
causes the motor to act as a gene rator during deceleration. See also four-quadrant operation  
and  dynamic braking.
Break-away 
TorqueThe torque a motor must produce to overcome the st atic friction of a load in order to start the 
load moving.
Carrier 
FrequencyThe frequency of the constant, periodic, switch ing waveform that the inverter modulates to 
generate the AC output to the motor. See also  PWM.
CEA regulatory agency for governing the performan ce of electronic products in Europe. Drive 
installations designed to have CE approval must ha ve particular filter(s) installed in the applica-
tion.
ChokeAn inductor that is tuned to re act at radio frequencies is called a “choke,” since it attenuates 
(chokes) frequencies above a particular threshol d. Tuning is often accomplished by using a 
movable magnetic core. In vari able-frequency drive systems, a choke positioned around high-
current wiring can help  attenuate harmful harmonics and protect equipment. See also  harmon-
ics .
DC BrakingThe inverter DC braking feature stops the AC  commutation to the motor, and sends a DC 
current through the motor windings in order to  stop the motor. Also called “DC injection 
braking,” it has little effect at high speed,  and is used as the motor is nearing a stop.
DC LinkThe portion of the variable frequency drive betwee n the input rectifiers and the output stages. It 
delivers smoothed DC power to the c ontrol and output stages of the drive.
DeadbandIn a control system, the range of input change for which there is no perceptible change in the 
output. In PID loops, the error term may have a  deadband associated with it. Deadband may or 
may not be desirable;  it depends on the needs of the application.
Digital Operator 
PanelFor Hitachi inverters, “digital operator panel” ( DOP) refers first to the operator keypad on the 
front panel of the inverter. It also includes  hand-held remote keypads, which connect to the 
inverter via a cable. Finally, the DOP Professi onal is a PC-based software simulation of the 
keypad devices.

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							SJ7002 Inverter
Appendix A
A–3
DiodeA semiconductor device that has a voltage-current characteristic that allows current to flow 
only in one direction, with negligible leakage current in th e reverse direction. See also rectifier.
Duty Cycle1. The percent of time a square wave of fixed frequency is ON (high) versus OFF (low).  2. The 
ratio of operating time of a motor, braking resi stor, etc. to its resting time. This parameter 
usually is specified in association with the allowable thermal rise for the device.
Dynamic BrakingThe inverter dynamic braking feature shunts th e motor-generated EMF energy into a special 
braking resistor. The added dissipation (braking to rque) is effective at higher speeds, having a 
reduced effect as the motor nears a stop.
ErrorIn process control, the error is the difference be tween the desired value or setpoint (SP) and the 
actual value of a the process variable (PV). See also  process variable and PID Loop.
EMIElectromagnetic Interference -  In motor/drive systems, the switching of high currents and 
voltages creates the possibility of  generating radiated electrical noise that may interfere with 
the operation of nearby sensitive el ectrical instruments or devices. Certain aspects of an instal-
lation, such as long motor lead wire lengths,  tend to increase the chance of EMI. Hitachi 
provides accessory filter components you ca n install to decrease the level of EMI.
Four-quadrant
operationReferring to a graph of torque versus speed, a four-quadrant drive can turn the motor either 
forward or reverse, as well as decelerate in either direction (see also reverse torque ). A load that 
has a relatively high inertia and must move in  both directions and change directions rapidly 
requires four-quadrant capability from its drive.
Free-run StopA method of stopping a motor, caused when the  inverter simply turns OFF its motor output 
connections. This may allow the motor and load  to coast to a stop, or a mechanical brake may 
intervene and shorten the deceleration time.
Frequency 
SettingWhile frequency has a broad mean ing in electronics, it typically refers to motor speed for 
variable-frequency drives (inverte rs). This is because the output frequency of the inverter is 
variable, and is proportional to  the attained motor speed. For example, a motor with a base 
frequency of 60 Hz can be speed controlled with  an inverter output varying form 0 to 60 Hz. 
See also  base frequency , carrier frequency , and slip.
HarmonicsA harmonic  is a whole number multiple of a base of fundamental frequency. The square waves 
used in inverters produce high -frequency harmonics, even though th e main goal is to produce 
lower-frequency sine waves. Thes e harmonics can be harmful to electronics (including motor 
windings) and cause radiated energy that interfere s with nearby electronic devices. Chokes, line 
reactors, and filters are sometimes used to suppress the transmissi on of harmonics in an electri-
cal system. See also c hoke.
HorsepowerA unit of physical measure to quantify the amou nt of work done per unit of time. You can 
directly convert between horsepower and Watts as measurements of power.
IGBTInsulated Gate Bipolar Transistor  (IGBT) - A semiconductor transistor capable of conduct-
ing very large currents when in saturation and capable of withstanding very high voltages when 
it is OFF. This high-power bipolar transistor  is the type used in Hitachi inverters. 
InertiaThe natural resistance of an object to being acce lerated or decelerated by an external force. See 
also  momentum .
Intelligent 
TerminalA configurable input or output l ogic function on the Hitachi inve rters. Each terminal may be 
assigned one of several functions.
InverterA device that electronically changes DC to AC  current through a alternating process of switch-
ing the input to the output, inverted and non-inve rted. A variable speed drive such as the Hitachi 
SJ700
2 is also called an inverter, since it contains  three inverter circuits to generate 3-phase 
output to the motor.

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