Omron K8AB-VW Manual page 10

Questions and Answers
Q
Checking Operation
Overvoltages
Gradually increase the input from 80% of the setting.
The input will equal the operating value when the input
exceeds the setting and the alarm indicator starts flashing.
Operation can be checked by the relay outputs that will
start after the operating time has passed.
Undervoltage
Gradually decrease the input from 120% of the setting and
check the operation using the same method as for
overvoltage.
Example: Overvoltage Operating Mode, Undervoltage Operating
Mode and an Operating Time of 5 s
Note: K8AB-VW@ output relays are normally operative.
Set value
Input voltage
Alarm indicator
Relay output
Connection Diagram
200 VAC
V
Variable
autotransformer
±
C 200 V
Cycle counter
Q
How to Measure the Operating Time
Overvoltage
Change the input suddenly from 0% to 120% of the set
value and measure the time until the Unit operates.
Undervoltage
Change the input suddenly from 120% to 0% of the set
value and measure the time until the Unit operates.
Grounding the Power Supply for K8AB Models with a DC
Q
Power Supply
The input and power supply must be isolated.
Models with a DC power supply have a non-isolated power
supply. The input and power supply are connected internally
so the K8AB-VW@ will not operate normally if an unwanted
current path exists. If an unwanted current path exists, use a
K8AB model with an AC power supply or use an isolated DC
power supply.
10
Single-phase Voltage Relay
Lit
Flashing
5 s
Input terminals
0 to 300 V
A1
Power supply
A2
K8AB-VW
Q
Using Multiple K8AB Relays with a DC Power Supply
The input and power supply must be isolated. The input and
power supply are connected internally so an unwanted
current path will be created if more than one K8AB is used
with one DC power supply, as shown in the diagram, and the
K8AB will not operate correctly. If an unwanted current path
exists, use a K8AB model with an AC power supply or use a
different isolated DC power supply for each K8AB.
K8AB
Input signal
Input ground
Q
Operating Adjustment Knobs
Use a screwdriver to turn the knobs. There is a stopper to
prevent the knob from turning any further once it has been
turned completely to the left or right. Do not force the knob
past these limits.
Q
Setting the Pre-alarm Monitoring Mode
Use the DIP switch to set the operating mode pins both to
overvoltage (SW3 ON and SW4 OFF) or both to
undervoltage (SW3 OFF and SW4 ON).
Example: Both Pins Set to Overvoltage
AL1 can be used as the pre-alarm for AL2 by
setting a smaller voltage set value for AL1 than for
AL2.
24 VDC
power supply
K8AB
Cat. No. N144-E1-02