K2CM
8
Nomenclature
10 (side) 9
6
7
8
R S T
R S T
1 pass
2 passes
Current-setting Knob
•
By operating the setting knob, set the current value to
be equal to the rated current of the motor to be used.
The current-setting knob uses the same scale as the
rated current. Therefore, the operating value will be
115% of the set current value.
Example: Operating current value
= 12
×
1.15 (115%) = 13.8 A
•
The List of Current Settings shows an example. The
rated current differs depending on the motor’s type,
construction, manufacturer, etc. Therefore, set the
operating current after checking the specifications of
the motor.
Trip Indicator
In normal operation, only the upper half of the display window is colored orange,
whereas when the motor circuit has tripped, the entire display window becomes orange.
Time-setting knob*
Reset Button
•
With manual resetting models, when the motor circuit trips during
normal operation or test operation, the operation indicators and
the output relay can be immediately reset by pressing the reset
button.
•
When the motor circuit trips due to reverse-phase with automatic
resetting models, the operation indicators and the output relay can
be immediately reset by pressing the reset button.
•
Reset button operation is ineffective when the operation power
supply is OFF. When the motor circuit trips during normal opera-
tion, identify the abnormal input function by checking the LED indi-
cators, then turn OFF the power switch of the main circuit and
proceed with troubleshooting. After the abnormality is removed,
turn ON the power switch of the main circuit to reset the K2CM.
Test Button
Inverse Type
•
Operation checks of the overcurrent function can be performed.
•
Pressing the test button for the time-setting value will cause the motor
circuit to trip.
•
With manual resetting models, even if the test button is released after
the motor circuit has tripped, the circuit remains tripped, whereas with
automatic resetting models, the motor circuit continues operating and
the output relay releases.
•
Be sure to perform the test operation with the overcurrent switch set to
ON. Set both the open-phase and reverse-phase switches to OFF. If
one of these switches is set to ON, the motor circuit may trip if an
open-phase or reverse-phase occurs before an overcurrent does.
Instantaneous Type
•
Perform the test operation with input current at 0 and the overcurrent
switch set to ON.
•
Pressing the test button for the set start-up lock time will cause the
motor circuit to trip.
•
With manual resetting models, even if the test button is released after
the motor circuit has tripped, the circuit remains tripped, whereas with
automatic resetting models, the motor circuit continues operating and
the output relay releases.
Deciding the Number of Primary Conductor Passes
•
When using a motor with a small current rating, decide the num-
ber of primary conductor passes through the current transformer
holes and the tap setting by referring to the List of Current Set-
tings.
•
Pass all the three wires through the respective holes of the current
transformer. Basically, the wires should be passed through the
specified holes. If this is difficult, however, they can be passed
through any holes provided that the phase order is R, S, and T.
•
If the wires are passed through the holes only once, a current within
the full scale of the current-setting knob can be set. If they are
passed more than once, however, the current setting range will
change according to the number of passes. The current setting
range when the number of conductor passes is n can be obtained
by dividing the full scale of the current-setting knob by n. For exam-
ple, the current setting range of the K2CM-
@@
L
@
is 8 to 26 A when
the wires are passed only once. This range is 4 to 13 A when the
wires are passed twice, 2 to 6.5 A when the wires are passed four
times, and 1 to 3.25 A when the wires are passed eight times.
The wires can be passed through the holes any number of times. It
is convenient for the calculation, however, if the number of passes
is 2, 4, or 8.
•
The signal from a high-voltage motor is input to the Motor Protec-
tive Relay via an external current transformer. In this case, the cur-
rent can be set in the same manner as above by dividing the rated
current of the high-voltage motor by the transformation ratio of the
current transformer.
Time-setting Knob
•
Set the required operating time by operating the time-setting knob.
(With instantaneous-type models, the set operating time is used as the
start-up lock time).
Note: 1.
The setting scale is the op-
erating time when 600% of
the current value is input.
2.
The required operating
time varies depending on
the type of motor, load con-
dition, etc. You can take the
time from when the motor
starts to when the motor
enters the steady state as
a guide for setting this val-
ue. When setting the oper-
ating time for submersible
motors, which require very
short operating times, con-
sult the manufacturer to
obtain the correct operat-
ing time. An operating time
shorter than 5 s can be
used as a rough guide.
•
The scale multiplying factor
can be selected by the time
scale multiplying factor
switch.
Scale
multiplying
factor
Time scale
multiplying factor
switch
Time scale
value
×
1 (s)
×
4 (s)
2
2
8
3
3
12
4
4
16
5
5
20
6
6
24
7
7
28
8
8
32
9
9
36
10
10
40
