Hitachi Sj7002 Owners Manual

Using Intelligent Output Terminals
Operations
and Monitoring
4–50
Examples 3 and 4 relate to configuring the inverter to retry upon power failure. Frequency 
matching is possible if the inverter frequency is  greater than the B007 value. In this case, the 
inverter reads the motor RPM and direction. If  this speed is higher than the matching setting 
(B007), the inverter waits until they are equal  and then engages the output to drive the motor 
(example 3). If the actual motor speed is less th an the...

SJ7002 Inverter
Operations
and Monitoring
4–51
To r q u e  L i m i t  
Signal   The Torque Limit output [TRQ] work s in conjunction with the torque limit function covered in 
the intelligent input section. The torque limit function limits the motor torque according to the 
criteria selected by parameter  B040. When torque limiting occurs, the [TRQ] output turns ON, 
then turns OFF automatically when the output torque falls below the specified limits. Note that 
the Torque Limit input [TL] must be ON in...

Using Intelligent Output Terminals
Operations
and Monitoring
4–52
Thermal Warning 
Signal   The purpose of the electronic thermal setti ng is to protect the motor from overloading, 
overheating and being damaged. The setting is base d on the rated motor current. The inverter 
calculates the thermal rise (heating) of the moto r using the current output to the motor squared, 
integrated over the time spent at those levels. This feature allows the motor to draw excessive 
current for relatively short...

SJ7002 Inverter
Operations
and Monitoring
4–53
Constant Torque Characteristic  – Selecting the constant torque characteristic for the example 
motor gives the curves below. At 2.5 Hz, the outp ut current is reduced by a factor of 0.9 for 
given trip times.
Free Thermal Characteristic  - It is possible to set the electronic thermal characteristic using a 
free-form curve defined by three data  points, according to the table below.
The left graph below shows the region for possi ble free-setting curves....

Using Intelligent Output Terminals
Operations
and Monitoring
4–54
Brake Control
Signals   The Brake Control function enables the inverter to control external braking systems with a 
particular safety characteristic. The brake releas e logic convention is such that an open circuit 
fault (such as loose wire) causes the external brake to engage. A complete discussion of the 
operation of brake control is in  “
External Brake Control Function” on page 4–32. The diagram 
below shows the signals that are...

SJ7002 Inverter
Operations
and Monitoring
4–55
Analog 
Disconnect
Detection   The analog disconnect dete ction is useful when the inverter  receives a speed reference from an 
external device. Upon input signal loss at either the [O], [OI], or [O2] terminal, the inverter 
normally just decelerates the motor to a stop.  However, the inverter can use the intelligent 
output terminals [ODc],  [OIdc], or [O2dc] to signal othe r machinery that a signal loss has 
occurred.
Each analog disconnect output has...

Using Intelligent Output Terminals
Operations
and Monitoring
4–56
PID Feedback 
Second Stage 
Output   The inverter has a built-in PID loop feature for tw o-stage control, useful for certain applications 
such as building ventilation or heating and cool ing (HVAC). In an ideal control environment, a 
single PID loop controller (stage) would be  adequate. However, in certain conditions, the 
maximum output energy from the first stage is  not enough to maintain the Process Variable 
(PV) at or near the...

SJ7002 Inverter
Operations
and Monitoring
4–57
To use the PID Second Stage Output feature, you  will need to choose upper and lower limits for 
the PV, via C053 and C052 respectively. As th e timing diagram below shows, these are the 
thresholds Stage #1 inverter uses to turn ON  or OFF Stage #2 inverter via the [FBV] output. 
The vertical axis units are perc ent (%) for the PID setpoint, and for the upper and lower limits. 
The output frequency, in Hz, is  superimposed onto the same diagram.
When system...

Using Intelligent Output Terminals
Operations
and Monitoring
4–58
Logic Output 
Signals   The Logic Output Function uses the inverter’s bu ilt-in logic feature. You can select any two of 
the other intelligent output options for use as in ternal inputs to the logic function. You may also 
select from three logical operators AND, OR, or XOR  (exclusive OR), to be applied to the two 
inputs. A total of six outputs are avai lable, shown in the following tables.
The example below shows a configuration for...

SJ7002 Inverter
Operations
and Monitoring
4–59
Low Cooling Fan 
Speed   The inverter monitors the heat  sink cooling fan speed to help prevent overheating. If the speed 
of the fan(s) decreases to 75% or less of full speed, output [WAF] Low Cooling Fan Speed 
turns ON. Note that if you set parameter B092  Cooling Fan Control = 01 (Fan ON only during 
RUN), the inverter will not output the [WAF ] signal when the cooling fan is stopped.
If the [WAF] signal turns ON during operation,  first check the...