Datasheet
K8AK-PW
8
Checking Operation
Overvoltage
Gradually increase the input from 80% of the set value.
The input value will equal the operating value when the input
exceeds the set value 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 set value 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: K8AK-PW@ output relays are normally operative.
Connection Diagram
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
K8AK terminals is 120% of the overvoltage set value or 80%
of the undervoltage set value when the auxiliary relay
operates in a test circuit. Close the switch and use the cycle
counter to measure the operating time.
Connection Diagram
Overvoltage Detection When Only One Phase Exceeds the
Overvoltage Set Value
The K8AK monitors each of the three-phase voltages. This
means an overvoltage is detected even if only one phase
exceeds the set value. The same applies to undervoltages.
Questions and Answers
Q
Set value
Input voltage
Alarm indicator
Relay output
Flashing
Lit
5 s
0 to 150 V
V1
Three-phase
variable autotransformer
L1
L2
L3
3φ,
200 VAC
V2 V3
L1
L2
L3
Overvoltage
Undervoltage
Q
L1
L2
L3
±
C 200 V
Cycle counter
V1
V2 V3
X
X/a
X/b
L1
L2
L3
R1
R2
R1: Slide resistor
200 Ω 200 W
R2: 100 Ω 400 W
3φ,
200 VAC
Q