Analog Input Disconnect Detect - Hitachi L2002 Instruction Manual

Analog Input Disconnect Detect

This feature is useful when the inverter receives a speed reference from an external
device. Upon input signal loss at either the [O] or [OI] terminal, the inverter normally
just decelerates the motor to a stop. However, the inverter can use the intelligent output
terminal [Dc] to signal other machinery that a signal loss has occurred.
Voltage signal loss at [O] terminal - Parameter B082 is the Start Frequency Adjust-
ment. It sets the beginning (minimum) output frequency when the speed reference
source is greater than zero. If the analog input at terminal [O] is less than the Start
Frequency, the inverter turns ON the [Dc] output to indicate a signal loss condition.
Current signal loss at [OI] terminal - The [OI] terminal accepts a 4mA to 20mA
signal, with 4mA representing the beginning of the input range. If the input current falls
below 4mA, the inverter applies a threshold to detect signal loss.
Note that a signal loss is not an inverter trip event. When the analog input value is again
above the B082 value, the [Dc] output turns OFF. There is no error condition to clear.
Option Terminal
Code Symbol
06 Dc Analog Input
Disconnect Detect
11, 12, AL0 – AL2
Valid for outputs:
A001=01, B082
Required settings:
Notes:
•
The [Dc] output can indicate an analog signal
disconnect when the inverter is in Stop Mode, as
well as Run Mode.
•
The example circuit for terminal [12] drives a relay
coil. Note the use of a diode to prevent the negative-
going turn-off spike generated by the coil from
damaging the inverter's output transistor.
Output
Function Name
State
ON
OFF
L200
Description
when the [O] input value < B082 Start
Frequency Adjustment (signal loss detected), or
when the [OI input current is less than 4mA
when no signal loss is detected
Example (requires output configuration—
see page 3–54):
Inverter output
terminal circuit
+
Example for terminals [AL0], [AL1], [AL2]
(requires output configuration—
4–36
see pages and 3–54):
Inverter logic
circuit board
AL0
Power
See I/O specs
supply
on page 4–6.
4–45
Inverter
2
Dc
CM2 12 11
RY
–
Dc
AL1 AL2
Load