Omron K2CU - User manual

1
Heater Element Burnout Detector K2CU
Accurate Detection of Heater Element
Burnout Regardless of Heater
Capacities
Accurately detects a burned heater element or
elements incorporated by a molding machine or
packing machine and outputs an alarm signal.
Precisely singles out the burned element even if
one heater element among several heater
elements has been burned out.
Applicable to small- to large-capacity heater
elements.
All K2CU-F large-capacity, built-in current trans-
former models work with both single-phase and
three-phase heaters.
Voltage fluctuation compensation function elimi-
nates false alarms due to variations in the supply
voltage.
Ordering Information
K2CU-FjjA-jGS Model with Gate Input Terminals
Control supply voltage Operating current
4 to 10 A 8 to 20 A 16 to 40 A 32 to 80 A
100 V AC W ith voltage fluctuation K2CU-F10A-CGS K2CU-F20A-CGS K2CU-F40A-CGS K2CU-F80A-CGS
1 10 V AC compensation K2CU-F10A-DGS K2CU-F20A-DGS K2CU-F40A-DGS K2CU-F80A-DGS
200 V AC K2CU-F10A-EGS K2CU-F20A-EGS K2CU-F40A-EGS K2CU-F80A-EGS
220 V AC K2CU-F10A-FGS K2CU-F20A-FGS K2CU-F40A-FGS K2CU-F80A-FGS
K2CU-F Large-capacity, Built-in Current Transformer Models
Control supply voltage Operating current
4 to 10 A 8 to 20 A 16 to 40 A 32 to 80 A
100 V AC W ith voltage fluctuation K2CU-F10A-C K2CU-F20A-C K2CU-F40A-C K2CU-F80A-C
1 10 V AC compensation K2CU-F10A-D K2CU-F20A-D K2CU-F40A-D K2CU-F80A-D
200 V AC K2CU-F10A-E K2CU-F20A-E K2CU-F40A-E K2CU-F80A-E
220 V AC K2CU-F10A-F K2CU-F20A-F K2CU-F40A-F K2CU-F80A-F
K2CU-P Small-capacity, Plug-in Models
Control supply voltage Operating current
0.25 to 0.5 A 0.5 to 1 A 1 to 2 A 2 to 4 A
100/
200 V AC W
ith voltage fluctuation
compensation K2CU-P0.5A-A K2CU-P1A-A K2CU-P2A-A K2CU-P4A-A
W ithout voltage
fluctuation compensation
--- K2CU-P1-A K2CU-P2-A K2CU-P4-A
110/
220 V AC W
ith voltage fluctuation
compensation K2CU-P0.5A-B K2CU-P1A-B K2CU-P2A-B K2CU-P4A-B
W ithout voltage
fluctuation compensation
--- K2CU-P1-B K2CU-P2-B K2CU-P4-B

K2CU K2CU
2
Specifications
Ratings
Item K2CU-F K2CU-P
Control supply voltage 100, 1 10, 200, 220 V AC 100/200, 1 10/220 V AC
Rated frequency 50/60 Hz
Carry current 1.25 times as large as each model’ s
maximum operating current
2.5 A for K2CU-P0.5A-A/-B;
5 A
Operating voltage range 85% to 1 10% of control supply voltage
V oltage fluctuation compensation
range
85% to 1 10% of control supply voltage 85% to 1 10% of control supply voltage
(applicable only on models with voltage
fluctuation compensation)
Operating current 4 to 10 A, 8 to 20 A, 16 to 40 A, 32 to 80 A
(continuously variable)
0.25 to 0.5 A, 0.5 to 1 A, 1 to 2 A, 2 to 4 A
(continuously variable)
Releasing current 105% max. of operating current 1 10% max. of operating current
Operate time 0.5 s max. (when current changes from 150% to 0%)
Gate input voltage range (for
models with gate input terminals)
5 to 30 VDC ---
Control output 2 A at 220 V AC, SPDT (cosφ = 0.4)
Power consumption Input: 0.5 V A max.
Power supply: 5 V A max.
Input: 1 V A max.
Power supply: 4 V A max.
Characteristics
Setting accuracy ± 7% max.
Repeat accuracy ± 3% max.
Influence of temperature ± 10% max. (at 20 °C±30°C)
Influence of voltage Models without voltage fluctuation compensation:
± 3% max. of the value measured at the control supply voltage, on condition that the voltage
fluctuation is 85% to 1 10% of the control supply voltage
Models with voltage fluctuation compensation:
± 5% max. of the logical value, on condition that the voltage fluctuation is 85% to 1 10% of the
control supply voltage. (see note)
Influence of frequency ± 3% max. (at ± 5% of rated frequency)
Insulation resistance 10 M Ω min. (at 500 VDC) between electric circuits and mounting panel
Dielectric strength 2,000 V AC, 50/60 Hz for 1 min between electric circuits and mounting panel
Overcurrent 20 times of max. set value of operating current for 2 s
V ibration resistance Destruction: 16.7 Hz, 1-mm double amplitude for 10 min each in X, Y , and Z directions
Shock resistance Destruction: 100 m/s
2
(approx. 10G)
Ambient temperature Operating: –10 ° C to 55 ° C (with no icing)
Ambient humidity Operating: 45% to 85%
Weight K2CU-F: approx. 390 g; K2CU-P: approx. 300 g
Note: The logical value is an operating value within a range of 0.85 to 1.1 with a voltage fluctuation of 85% to 1 10%, based on the value at the
control supply voltage measured as 1.

K2CU K2CU
3
Operation
K2CU-F A- GS Series
When power is supplied to the heater (when the SSR is ON), a cur -
rent flows through the wires to the heater elements. At the same
time, a voltage is imposed on the gate circuit and the
K2CU-FjjAjGS begins monitoring the current flowing through
the
heater wires.
The current flowing to the heater wires is detected by the detector
sections through each Current Transformer (CT) incorporated by
the K2CU-FjjA-jGS.
The
current signals transmitted by the two CT s are sent to the cur -
rent-voltage converters, smoothing circuits, and comparators as
shown
in the diagram.
The signal generated by the reference voltage generator is sent to
the setting circuit to provide a reference value. The reference value
is sent to the comparators. Each comparator compares its heater
element
current input and the reference value. If the input is lower
than the reference value, a signal is sent to the output circuit.
There are two detector sections operating independently . If either of
the input signals from the CT s is lower than the reference value, the
output relay and alarm indicator will be activated.
The K2CU-FjjA-jGS incorporates a voltage fluctuation com-
pensation
function which automatically corrects the reference value
if the supply voltage fluctuates.
Current-
voltage
converter
Smoothing
circuit
Gate
circuit
Setting
circuit Reference voltage
generator
Power
circuit
Current-
voltage
converter
Smoothing
circuit
BZ
Output
circuit
Temperature
controller
XCM1
a1
b1
S2S1G–G+
CT1
CT2
SSR DC
Heater elements
Power source
X/c
Output relay
Alarm indicator
Buzzer
To each circuit
Note: 1. The dotted lines indicate the line conductors passing through the windows of the current transformers.
2. The current flowing into the gate circuit (between G+ and G–) is as follows:
Approximately 1.4 mA at 5 VDC
Approximately 3.4 mA at 12 VDC
Approximately 6.7 mA at 24 VDC
3 When using a K2CU which has the model number suf fix ”GS” (a model that incorporates gate input
terminals), the control output of the temperature controller must be a voltage output type.
Comparator
Comparator

K2CU K2CU
4
K2CU-F
Series
When power is supplied to the heater (when the contactor is ON), a
current flows through the wires to the heater elements. At the same
time, a voltage is imposed on the power circuit of the K2CU-F .
The current flowing to the heater wires is detected by the detector
sections through each Current Transformer (CT) incorporated by
the K2CU-F.
The
current signals transmitted by the two CT s are sent to the cur -
rent-voltage converters, smoothing circuits, and comparators as
shown
in the diagram.
The signal generated by the reference voltage generator is sent to
the setting circuit to provide a reference value. The reference value
is sent to the comparators. Each comparator compares its heater
element
current input and the reference value. If the input is lower
than the reference value, a signal is sent to the output circuit.
There are two detector sections operating independently . If either of
the input signals from the CT s is lower than the reference value, the
output relay and alarm indicator will be activated.
The K2CU-F incorporates a voltage fluctuation compensation func -
tion which automatically corrects the reference value if the supply
voltage
fluctuates.
Current-
voltage
converter
Smoothing
circuit Setting circuit Reference voltage
generator
Power
circuit
Current-
voltage
converter
Smoothing
circuit
BZ
Output
circuit XCM1
a1
b1
S2S1
CT1
CT2
Heater elements
Power source
X/c
Output relay
Alarm indicator
Buzzer
To each circuit
Comparator
Comparator
Note: The dotted lines indicate the line conductors passing through the windows of the current transformers.
Contactor
K2CU-P Series
The K2CU-P operates basically in the same way as the K2CU-F .
The comparator compares external current signals and the refer-
ence value and outputs the result of the comparison to the output
circuit.
Current-
voltage
converter
Smoothing
circuit Setting circuit
Power
circuit
BZ
Output
circuit X3
4
5
87
Comparator
Reference
voltage
generator
Heater elements
Power source
X/c
Output relay
Alarm indicator
To each circuit
Contactor
6
Buzzer
CT
1
2
200/220 V 100/110 V 0 V

K2CU K2CU
5
Setting of Operating Current
Use the potentiometer on the front panel to set the operating cur-
rent.
Rotate
the knob to set the desired current value at which the Heater
Burnout Detector should operate. Do not exceed the maximum and
minimum positions.
The K2CU-F’s scale is divided into 12 graduations including sub-
graduations
and the K2CU-P’ s scale is divided into 5 graduations.
The knobs of the K2CU-F and K2CU-P as shown in the illustrations
are set to 32 A and 0.7 A respectively .
The
set operating current is defined as the mean value of the heater
current under normal operating conditions and the heater current
under
a burnout or abnormal condition.
Set value =
Normal current + abnormal current
2
Knob
Red point
(indicates the set value)
Heater Connection and Current
The following table shows the dif ferent connections possible. The formula under each illustration indicates the electrical current value of the
heater elements under normal and abnormal conditions.
Phase Normal condition Abnormal condition
Single phase
200 V
5 A
5 A
1 kW 200 V
0 A
0 A
Three
phase Delta network 200 V
200 V
200 V
8.7 A
8.7 A
8.7 A
1 kW
1 kW
1 kW
(5 A x )
3
7.5 A
7.5 A
3
2
(5 A x x )
3
5 A
8.7 A
5 A
1
3
(5 A x x )
3
Star
network 200 V
200 V
200 V
2.9 A
2.9 A
2.9 A
1 kW
1 kW
1 kW
1
3
(5 A x )
2.5 A
2.5 A
3
2
(5 A x x )
1
3
2.5 A
2.5 A
3
2
(5 A x x )
1
3
V
network 200 V
200 V
200 V
5 A
8.7 A
5 A
1 kW
1 kW
(5 A x = 8.7 A)
3(5A x 1/2)
2.5 A
2.5 A
5 A
5 A
(5A x 1)
Note: Values in this table are correct when a 200 V AC, 1 kW heater is used on a single-phase or three-phase current.

K2CU K2CU
6
Operation Check
K2CU-F A- GS
The operation of the heater burnout detector can be easily checked
as follows:
In a Single-phase Circuit
Set the operating current to be 0.6 to 0.55 times the heater current.
Close the SW2with switch SW1 turned on. Confirm that the alarm
indicator remains of f.
Turn
of f SW
1
and confirm that the alarm indicator comes on, and that
the output relay operates.
K2CU-F
S1
S2
G+
G–
Heater
SW1
SSR
SW2
In a Three-phase, Delta Network
Set the operating current to be 0.6 times the heater current.
Close the SW
3
with switches SW
1
and SW
2
turned on. Confirm that
the alarm indicator remains of f.
Turn
of f SW
2
and confirm that the alarm indicator comes on, and that
the output relay operates.
Turn on SW
1
set the operating current to be 0.9 times the heater cur -
rent, and confirm that the alarm indicator goes off and the output
relay
releases.
Turn of f SW
1
and confirm that the alarm indicator comes on, and that
the output relay operates.
G+
G–
S1
S2
K2CU-F
Heater
SW1
SSR
SW3
SW2
In a Three-phase, Star Network
Set the operating current to be 0.9 times the heater current.
Close the SW2with switch SW1 turned on. Confirm that the alarm
indicator remains of f.
Turn
of f SW
1
and confirm that the alarm indicator comes on, and that
the output relay operates.
G+
G–
S1
S2
K2CU-F
Heater
SW1
SSR
SW2

K2CU K2CU
7
In a Three-phase, V Network 1
Set the operating current to be 0.3 to 0.35 times the heater current.
Close the SW2with switch SW1 turned on. Confirm that the alarm
indicator remains of f.
Turn off SW1 and confirm that the alarm indicator comes on, and
that
the output relay operates.
G+
G–
S1
S2
K2CU-F
Heater
SW1
SSR
SW2
In a Three-phase, V Network 2
Set the operating current to be 0.6 times the heater current (of the
phase connected between terminals 1 and 2, or the one passed
through
the window of the window-type Current T ransformer of the
heater burnout detector).
Close the SW2with switch SW1 turned on. Confirm that the alarm
indicator remains of f.
Turn off SW1 and confirm that the alarm indicator comes on, and
that
the output relay operates.
G+
K2CU-F
Heater
SSR
SW2
SW1
G–
S1
S2
K2CU-F, K2CU-P
The operation of the heater burnout detector can be easily checked
as follows:
In a Single-phase Circuit
Set the operating current to be 0.55 to 0.6 times the heater current.
Close the contactor with switch SW1turned on. Confirm that the
alarm
indicator remains of f.
Turn
of f SW
1
and confirm that the alarm indicator comes on, and that
the output relay operates.
K2CU-F
S1
S2
Heater
SW1
1
2
K2CU-P
Heater
SW1
Contactor Contactor

K2CU K2CU
8
In a Three-phase, Delta Network
Set the operating current to be 0.6 times the heater current.
Close the contactor with switches SW
1
and SW
2
turned on. Confirm
that the alarm indicator remains of f.
Turn
of f SW
2
and confirm that the alarm indicator comes on, and that
the output relay operates.
Turn on SW
1
set the operating current to be 0.9 times the heater cur -
rent, and confirm that the alarm indicator goes off and the output
relay
releases.
Turn of f SW
1
and confirm that the alarm indicator comes on, and that
the output relay operates.
S1
S2
K2CU-F
Heater
SW2
SW1
Contactor
In a Three-phase, Star Network
Set the operating current to be 0.9 times the heater current.
Close the contactor with switch SW1turned on. Confirm that the
alarm
indicator remains of f.
Turn
of f SW
1
and confirm that the alarm indicator comes on, and that
the output relay operates.
Heater
S1
S2
K2CU-F
SW1
Contactor
In a Three-phase, V Network 1
Set the operating current to be 0.3 to 0.35 times the heater current.
Close the contactor with switch SW1turned on. Confirm that the
alarm
indicator remains of f.
Turn off SW1 and confirm that the alarm indicator comes on, and
that
the output relay operates.
S1
S2
Heater
K2CU-F
SW1
Contactor
In a Three-phase, V Network 2
Set the operating current to be 0.6 times the heater current (of the
phase connected between terminals 1 and 2, or the one passed
through
the window of the window-type Current T ransformer of the
heater burnout detector).
Close the contactor with switch SW1turned on. Confirm that the
alarm
indicator remains of f.
Turn off SW1 and confirm that the alarm indicator comes on, and
that
the output relay operates.
SW1
Contactor
1
2
K2CU-P
Heater
K2CU-P

K2CU K2CU
9
S1
S2
Heater
K2CU-F
SW1
Contactor
K2CU-F
Test Circuit
To check the operation in detail, use the following circuit.
S1
S2
b1
CM1
a1
Slidac
K2CU-F
SW1
R
Slidac
Switch
R
1
2
7
8
6
5
4
3
K2CU-P
Switch
The dotted lines indicate the line con-
ductor passing through the round
window of the current transformer.
Note: Determine the value of R according to the specifications
of the K2CU to be used. The dotted line indicates the
connection at a supply voltage of 100 or 1 10 V AC.
K2CU-F K2CU-P
Dimensions
Note: All units are in millimeters unless otherwise indicated.
K2CU-P
Connecting Socket
K2CU-P
8PFA1
108
89 78.5
60
7291
3.5
5

K2CU K2CU
10
K2CU-F
111
60
620
33
95
108
Eight,
M3.5
terminal
screws Two, 20-dia.
holes
6-dia. mounting
hole
Alarm
indicator
Potentiometer
knob
102 90
Mounting Holes
6.5 mm max.
102
Two, 6-dia. or M5
mounting holes
6.5 mm max.
Note: 1. Install the K2CU-F on a flat surface.
2. When solderless terminal lugs are
desired, use ones having an outer
diameter of 6.5 mm maximum.
Installation
External Connections
K2CU-F A- GS
Single-phase Heater Three-phase Heater
G+
G–
S1
S2
b1
CM1
a1
SSR
YBZL
Y/a
Heater
K2CU-F
G+
G–
S1
S2
b1
CM1
a1
YBZL
SSR
Temperature
sensor
Y/a
Heater
K2CU-F
Temperature
controller Temperature
controller
Power
source
Power
source
Control
voltage Control voltage
Temperature
sensor

K2CU K2CU
11
K2CU-F
Single-phase Heater Three-phase Heater
S1
S2
YBZL
CM1
a1 Y/a
Heater
K2CU-F
Temperature
controller
Power
source
S1
S2
YBZL
b1
CM1
al Y/a
Heater
K2CU-F
Temperature
controller
Power
source
Control
contact Control contact
Contactor Contactor
Temperature
sensor Temperature sensor
Three-phase, V -connected Heater W ith External Current T ransformer
S1
S2
b1
CM1
al
Heater
K2CU-F
S1
S2
b1
CM1
al
Heater
K2CU-F10A-j
Power
source
CT
jA/SA
CT
jA/SA
Note: Pass two out of the three line conductors
through the current transformers of the
heater burnout detector twice as shown.

K2CU K2CU
12
K2CU-P Small-capacity, Plug-in Models
Small-capacity Heater W ith External Current T ransformer
1
2
YBZL
7
8
6
5
4
3
Temperature
sensor
Y/a
Heater
K2CU-P
Temperature
controller
Power
source
Control
contact
7
8
1
2
YBZL
6
5
4
3
Temperature
sensor
Y/a
Heater
K2CU-P
Power
source
CT
jA/5 A
Temperature
controller Control
contact
Contactor
Note: 1. The dotted lines which pass through the heater burnout detector indicate the line conductor
passing through the round “window” of the window-type Current T ransformer.
2. Y:
External relay for self-holding circuit
BZ: Alarm buzzer
L: Alarm indicator
3. To use an 100 (1 10) V AC control power supply with K2CU-P , connect it to terminal 7 instead
of 6.
Precautions
K2CU-F A- GS
Use the K2CU-F jjA-j GS (with gate input terminals) in combina -
tion with a temperature controller that has PID with feed-forward cir -
cuitry to control the heater temperature, in which case, the heater
element(s)
must be turned ON or OFF for 0.1 s or longer .
K2CU-F
When a single-phase heater is used, pass the two lines through the
openings of the heater burnout detector . When a three-phase heat -
er is used, pass two (phases) of the three lines through the
open -
ings.
In either case, if only one line passes through, an alarm signal
will always be produced.
With single-phase
power supply
With three-phase
power supply
Heater
Heater
Pass the lines through the openings only once. If they are passed
more than once, the actual operating current will be less than the set
current. The lines can be passed in either direction.
To use the heater burnout detector at a current less than the current
range that can be set, the lines must be passed more than once. De -
termine
the number of times the lines should be passed by the fol -
lowing
equation:
(Operating current) x n = Current setting range
where,
n: number of times the lines loop through the window
All K2CU-F models incorporate a voltage fluctuation compensation
function.
K2CU-P
The K2CU-P can be used only in single-phase circuits.
Do not pull out the K2CU-P from the socket when the K2CU-P is en -
ergized. Especially when using it in combination with a Current
Transformer commercially available, this practice causes the sec-
ondary
circuit of the transformer to open, which is very dangerous.

K2CU K2CU
13
General
Refer to “ External Connections ” before using the K2CU with exter -
nal CTs.
When a temperature controller is used in combination with the
K2CU (except for the K2CU-FjjA-jGS), the heater element(s)
must
be turned ON or OFF for 1 s or longer (although the heater ele -
ment(s)
can be turned ON for 0.5 s according to the specifications).
The K2CU cannot be used with a phase-control circuit, inverter cir -
cuit,
frequency-count circuit, cycle-control unit, or a motor load.
Mounting
Securely mount the K2CU as horizontally as possible although
there
is no particular limitation of mounting directions.
Connection
Solderless-type terminal must be connected to the terminals se-
curely.
Wire
the terminals correctly by referring to the external connections.
The terminals have no polarity . Be sure to connect 100 (or 1 10) V to
the 100-V (or 1 10-V) terminals and 200 (or 220) V to the 200-V (or
220-V) terminals of the K2CU-P or the K2CU-P may malfunction.
The control power source for the K2CU (except for the
K2CU-FjjA-jGS)
must be supplied from the load side via a con -
tactor.
Be
sure to impose a voltage between the 0-V terminal and 100-V (or
110-V) terminal or the 0-V terminal and 200-V (or 220-V) terminal of
the K2CU-P , otherwise the K2CU-P will not operate.
Operating Current Setting when Several Heaters are Used
The following table shows relative values of changes in the current
when any one of several heaters connected in parallel has burned
out. The current value under normal condition is 1. Use this table as
a guideline in determining the operating current.
Connection n = 1 n = 2 n = 3 n = 4 n = 5
INo.
of heater = n
0 0.5 0.67 0.75 0.8
Current in burned-out phase 0 0.6 0.75 0.82 0.86
INo.
of heater
per phase = n
Current in other phases 0.87 0.92 0.95 0.96 0.97
Current in burned-out phase 0.58 0.77 0.84 0.88 0.91
I
No. of heater
per phase = n
Current in other phases 1 1 1 1 1
Note: 1. This table shows the respective change rates in current when any one of several heaters connected in parallel has burned out.
2. The current value under the normal condition is 1.
3. The values in this table are logical values. Actually , these values may vary slightly because of influence of unbalanced loads (heat -
ers).
It is therefore recommended to test the actual current values and the load condition before determining the operating current,
especially when the current under the normal condition and that under an abnormal condition do not significantly dif fer.

K2CU K2CU
14
OMRON Corporation
Measuring & Supervisory Controls Division
29th Fl., Crystal T ower Bldg.
1–2–27, Shiromi, Chuo-ku,
Osaka 540 Japan
Phone: [phone] Fax: [phone]
ALL DIMENSIONS SHOWN ARE IN MILLIMETERS.
To convert millimeters into inches, multiply by 0.03937. T o convert grams into ounces, multiply by 0.03527.
Cat. No. N39–E1–2 In the interest of product improvement, specifications are subject to change without notice.
Printed in Japan
0393–1M (0393)