Questions And Answers - Omron K8AB-PM Series Manual

Questions and Answers

Q
Checking Operation
Overvoltages
Gradually increase the input from 80% of the setting.
The input value will equal the operating value when the
input exceeds the setting and the alarm indicator starts
flashing. Operation can be checked by the relay output 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: For monitoring mode set to three-phase three-wire
monitoring, a rated voltage of 200 V, and an operating time
of 5 s.
Note: K8AB-PM@ output relays are normally operative.
Operating set value
Input voltage
Alarm indicator
Relay output
Connection Diagram 1
3φ,
200 VAC
L1
L2
L3
Three-phase variable
autotransformer
Cat. No. N146-E1-02
Flashing Lit
5 s
Overvoltage
L1
V1
L2
V2 V3
L3
0 to 150 V
Undervoltage
Three-phase Phase-sequence Phase-loss Relay
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.
Operating Time
Adjust the slide resistor so that the voltage applied to the
K8AB terminals is 120% of the set value (for overvoltage
detection) and 80% of the set value (for undervoltage
detection) when the auxiliary relay operates, as shown in
connection diagram 2. Close the switch and use the cycle
counter to measure the operating time.
Connection Diagram 2
3φ, 200 VAC
L1
X/a
X
L2
L3
±
C 200 V
Cycle counter
Q
Checking the Phase Sequence and Phase Loss
Operation
Phase Sequence
Switch the wiring, as shown by the dotted lines in
connection diagram 1, to reverse the phase sequence and
check that the K8AB operates.
Phase loss
Create a phase loss for any input phase and check that the
K8AB operates.
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.
L1
V1
L2
R1
V2 V3
X/b
L3
R2
R1: Slide resistor
200 Ω 200 W
R2: 100 Ω 400 W
K8AB-PM
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