4
Three-phase Phase-sequence Phase-loss Relay
K8AB-PM
Cat. No. N146-E1-02
Connections
■
Wiring Diagram
Overvoltage/Undervoltage and Phase Sequence/Phase Loss Operation Diagram
Operation Indicators
Note: 1.
While phase loss is detected, Over_Ry will also be OFF.
2.
The indicator flashes at 1-second intervals when reversed
phases are detected and at 0.5-second intervals during the
detection time.
Flashing
Lit
Flashing
Lit
O
v
er
v
oltage alarm indicator
Under
v
oltage setting
v
al
u
e
O
v
er
v
oltage
setting
v
al
u
e
Under
v
oltage alarm indicator
O
v
er
v
oltage relay
Under
v
oltage relay
Inp
u
t
Hysteresis: Fixed at 5%
Hysteresis: Fixed at 5%
T: Operating time (0.1 to 30 s)
T: Operating time (0.1 to 30 s)
T1: Po
w
er O
N
lock (1 s or 5 s)
Phase loss operation
Phase se
qu
ence operation
Flashing Flashing
Inp
u
t
Under
v
oltage alarm indicator
Under
v
oltage relay
L1
L3
L2
L3
L2
L1
L1
L2
L3
L1
L2
L3
T1
L1
L2
L3
T
T
Note: 1.
The K8AB-PM output relay is normally operative.
2.
The power ON lock prevents unnecessary alarms from being generated during the
instable period when the power is first turned on. There is no relay output during timer
operation.
3.
Phase loss is detected by L1, L2, and L3 voltage drops.
A phase loss will exist if any of the phases drops below 60
%
of the rated input.
4.
L1 and L2 function both as the power supply terminals and as input terminals. If the
voltage drops dramatically, then the Relay will not operate due to an undervoltage.
5.
Phase loss on the power supply or load side cannot be detected in the motor load
during operation.
Item
Display
Contact operation
Ry_LED Over_LED Under_LED Over_Ry Under_Ry
Over-
voltage
ON
ON
OFF
OFF
ON
Under-
voltage
ON
OFF
ON
ON
OFF
Phase
loss
OFF
OFF (See
note 1.)
ON
OFF
(See note
1.)
OFF
Re-
versed
phase
ON
OFF
Flashing
(See note
2.)
ON
OFF
Correct
phase
ON
OFF
OFF
ON
ON
Load
Voltage inp
u
t
Signal o
u
tp
u
t
14
12
L1
L2
L3
11
L1
N
L2 L3
Signal o
u
tp
u
t
24
22
21
Under
v
oltage
Phase loss,
re
v
ersed phase
O
v
er
v
oltage
N
