NEW Product
1
Thermistor Motor Protection Relay
K8AK-TS/-PT
Monitor Temperature Rise through
Internal Motor Loss
• Temperature, phase sequence, and phase loss monitoring with
the DIN 22.5-mm-sized K8AK-PT Relays.
• Side-by-side mounting of K8AK-PT Relays.
• Specially designed for internal motor monitoring; no setting
required.
• Test/Reset Button for confirmation of output operation.
• Monitoring also performed for thermistor disconnections and
short circuits.
• Manual or automatic resetting with the same Relay.
Ordering Information
List of Models
Refer to Safety Precautions on page 8.
Refer to page 7 for commonly asked questions.
For the most recent information on models that have been certified for
safety standards, refer to your OMRON website.
Function Power supply voltage Model
Phase sequence, phase loss, and temperature monitoring
100 to 240 VAC
K8AK-PT1 100-240 VAC
Temperature monitoring
K8AK-TS1 100-240 VAC
24 VAC/DC K8AK-TS1 24 VAC/DC
K8AK-TS/-PT
2
Ratings and Specifications
Ratings
Power supply
voltage Isolated power supply 24 VAC/DC
100 to 240 VAC
Power consumption 24 VAC/DC: 1.8 VA/1.0 W max.
100 to 240 VAC: 3.5 VA max.
Rated input voltage 3-phase, 200 to 480 VAC (3-wire)
Operating time
Phase sequence on three-
phase voltage input 0.1 s±0.05 s
Phase loss on three-phase
voltage input 0.1 s max. (when the voltage changes rapidly from 100% to 0% of rated voltage)
PTC thermistor input 0.2 s max.
Reset method Manual reset/automatic reset (switchable)
Note: Manual reset method: Press the TEST/RESET button.
Indicators Power (PWR): Green, PH_Alarm outputs (ALM): Red, TS_Alarm outputs (ALM): Red
Output relays One SPDT relay output (normally closed operation)
Output relay ratings
Rated load
Resistive load
5 A at 250 VAC
5 A at 30 VDC
Maximum switching capacity: 1,250 VA, 150 W
Minimum load: 5 VDC, 10 mA (reference values)
Mechanical life: 10 million operations min.
Electrical life: 5 A at 250 VAC or 30 VDC: 50,000 operations
3 A at 250 VAC or 30 VDC: 100,000 operations
Ambient operating temperature −20 to 60°C (with no condensation or icing)
Storage temperature −25 to 65°C (with no condensation or icing)
Ambient operating humidity 25% to 85% (with no condensation)
Storage humidity 25% to 85% (with no condensation)
Altitude 2,000 m max.
Terminal screw tightening torque 0.49 to 0.59 N·m
Terminal wiring method
Recommended wire
Solid wire: 2.5 mm2
Twisted wires: AWG16, AWG18
Note: 1. Ferrules with insulating sleeves must be used with twisted wires.
2. Two wires can be twisted together.
Recommended ferrules
Al 1,5-8BK (for AWG16) manufactured by Phoenix Contact
Al 1-8RD (for AWG18) manufactured by Phoenix Contact
Al 0,75-8GY (for AWG18) manufactured by Phoenix Contact
Case color N1.5
Case material PC and ABS, UL 94 V-0
Weight Approx. 150 g
Mounting Mounts to DIN Track.
Dimensions 22.5 × 90 × 100 mm (W×H×D)
K8AK-TS/-PT
3
Specifications
Allowable operating voltage range 85% to 110% of rated power supply voltage
Allowable operating frequency range 50/60 Hz ±5 Hz
Input frequency 50/60 Hz
Input overload capacity Continuous 528 V
Phase loss detection level
80%±10% of rated input
If any phase-to-phase voltage drops to 80%±10% of the other phase-to-phase voltages,
voltage asymmetry is detected and the phase loss function is performed.
PTC thermistor
Operating value precision 3,100 Ω ±5%
Reset value precision 1,650 Ω ±5%
Short circuit detection value
precision 0 to 10 Ω ±5 Ω
Temperature drift ±0.1%/°C max.
Operating time repeatability ±50 ms
Applicable stan-
dards
Conforming standards EN 60947-5-1
Installation environment (pollution level 2, installation category III)
EMC EN 60947-5-1
Safety standards UL 508 (Recognition), Korean Radio Waves Act (Act 10564),
CSA: C22.2 No.14, CCC: GB14048.5
Insulation resistance
20 MΩ min.
Between external terminals and case
Between power supply terminals and input terminals
Between power supply terminals and output terminals
Between input terminals and output terminals
Dielectric strength
2,000 VAC for one minute
Between external terminals and case
Between power supply terminals and input terminals
Between power supply terminals and output terminals
Between input terminals and output terminals
Noise immunity 1,500 V power supply terminal common/normal mode
Square-wave noise of ±1 µs/100 ns pulse width with 1-ns rise time
Vibration resistance Frequency: 10 to 55 Hz, acceleration 50 m/s2
10 sweeps of 5 min each in X,Y, and Z directions
Shock resistance 100 m/s2, 3 times each in 6 directions along 3 axes
Degree of protection Terminals: IP20
K8AK-TS/-PT
4
Connections
Terminal Diagram
Note: 1. Terminal application depends on the model.
2. Do not connect anything to terminals that are shaded in gray.
3. The T1, T2, and Y1 terminals are not isolated from the three-phase voltage input (L1, L2, and L3), which carries a hazardous voltage
(480 V max.). Use cables with reinforced insulation for wiring and connect a class II device (e.g., switch).
Class II: Double or reinforced insulation is used to provide protection from electric shock, and a ground is not required.
4. Use the recommended ferrules if you use twisted wires.
Wiring Example
Note: There is no polarity for the DC voltage input.
L1 L2 L3
A1
A2
11 12
Control Output
Input Range
Output Method
Relay output
250 VAC, 5 A (resistive load)
30 VDC, 5 A (resistive load)
PTC thermistor
Common
Open/closed
14
T1 T2 Y1
PTC Thermistor Input
B Power Supply Voltage
100 to 240 VAC 24 VAC/DC
(No polarity)
K8AK-TS (without 3-phase input)
K8AK-PT (with 3-phase input)
No terminals
A Three-phase Input
Y1-T2 open
Automatic output reset
Y1-T2 closed
Manual output reset
3-phase input
3-phase, 200 to 480 VAC
K8AK-PT1 100-240VAC
AB
T1 T2 Y1
L1
L1
L2
L3
L2 L3
A1 A2 A1 A2
Common
Relay Output
11 12 14
3-phase
voltage
Power
supply voltage
A1 A2
11 12 14
L1 L2 L3
T1 T2 Y1
A1
A2
Motor
Power
supply
AC/DC
K8AK-TS/-PT
5
Nomenclature
Front ●Indicators
●Keys
Note: 1. Use either a solid wire of 2.5 mm2 maximum or a ferrule with
insulating sleeve for the terminal connection.
The length of the exposed current-carrying part inserted into
the terminal must be 8 mm or less to maintain dielectric
strength after connection.
Recommended ferrules
Phoenix Contact
•Al 1,5-8BK (for AWG16)
•Al 1-8RD (for AWG18)
•Al 0,75-8GY (for AWG18)
2. Tightening torque: 0.49 to 0.59 N·m
Operation Methods
Setting the Output Reset Method
Use the Y1 and T2 terminals to set the output reset method.
Y1-T2 Terminal Operation
TEST/RESET Key Operation
●Testing
Automatic Output Reset
If the key is pressed during normal status, the relay output and alarm indicator will go to error status but only while the key is held in.
Manual Output Reset
If the key is pressed during normal status, the relay output and alarm indicator will go to error status.
●Resetting
Manual Output Reset
If the key is pressed when the output and alarm indicator are in alarm status and the input is normal, the output and alarm indicator will return
to normal status.
●PTC Thermistor Input Hysteresis
There is hysteresis between the operating value and the reset value.
If the input value exceeds the operating value and an error is detected, normal status is not restored until the input value goes below the reset
value.
However, if the input value is between the operating value and reset value and an error is being detected, normal status is restored if the control
power supply is cycled.
Power indicator
Alarm indicator
Terminal block
(See notes 1 and 2.)
Terminal block
(See notes 1 and 2.)
T1 T2 Y1
11 12 14
2A 1A 2A 1A
T1 T2 Y1
L1 L2 L3
11 12 14
PH
ALM
PWR
TS
ALM
Thermistor &
3P-Sequence,
Loss Ry
TEST/
RESET
PT1
PWR
TS
ALM
Thermistor Ry
TEST/
RESET
TS1 K8AKK8AK
K8AK-TS1 K8AK-PT1
TEST/RESET key
Item Meaning
Power indicator
(PWR: Green) Lit when power is being supplied.
Alarm
indica-
tor
PH_ALM = Red
Lit for phase loss on 3-phase input.
Flashing for phase sequence on 3-
phase input.
Lit in Test Mode.
TS_ALM = Red Lit for error in PTC thermistor input.
Lit in Test Mode.
Item Meaning
TEST/RESET key Press with your finger to per-
form tests and resets.
For 2.5 mm2 or
smaller solid wires
For ferrules with
an insulation sleeve.
8 mm max. 8 mm max.
Y1-T2 terminals Output reset method
Open Automatic reset
Closed Manual reset
K8AK-TS/-PT
6
Timing Charts
●Automatic Output Reset (Y1-T2: Open)
●Test Mode
●Manual Output Reset (Y1-T2: Closed)
●Using Y1-T2 as Remote Reset Terminals
Note: 1. It requires 0.1 s for the contacts to switch after the input status is detected. This is not shown in the diagram.
2. There are two types of error detection for the three-phase input. The indicator behavior changes accordingly.
Phase loss detected: PH_ALM lights.
Phase sequence detected: PH_ALM flashes.
If both a phase loss and phase sequence are detected at the same time, phase loss takes priority.
Dimensions (Unit: mm)
Thermistor Motor Protection Relays
Normal
3,100 Ω
1,650 Ω
10
Ω
Not
pressed.
t1 t1: Power ON lock (0.6 s)
Error
TS_ALM
PH_ALM
Relay contacts
(11-14)
TEST/RESET
key
PTC thermistor
input
Three-phase
input error
Power supply
voltage
Relay contacts
(11-14)
Manual output reset
Y1-T2 closed.* Automatic output reset
Normal
3,100 Ω
1,650 Ω
10
Ω
t1 * Test Mode can be used during normal status.
Error status is entered when the TEST/RESET key is
pressed.
The method to restore normal status is linked to the
output reset method.
TS_ALM
PH_ALM
TEST/RESET
key
PTC thermistor
input
Three-phase
input error
Power supply
voltage
Normal
t1: Power ON lock (0.6 s)
Normal
3,100 Ω
1,650 Ω
10
Ω
Not
pressed.
t1
Error
TS_ALM
PH_ALM
Relay contacts
(11-14)
TEST/RESET
key
PTC thermistor
input
Three-phase
input error
Power supply
voltage
t1: Power ON lock (0.6 s)
Open
Closed
Y1-T2 closed.*
* Output Reset Mode is entered when Y1-T1 closes.
The latched error status is cleared.
When Y1-T2 opens again, the initial status is restored.
3,100 Ω
1,650 Ω
10
Ω
t1
TS_ALM
PH_ALM
Relay contacts
(11-14)
TEST/RESET
key
PTC thermistor
input
Three-phase
input error
Power supply
voltage
t1: Power ON lock (0.6 s)
T1 T2 Y1
11 12 14
2A 1A 2A 1A
T1 T2 Y1
L1 L2 L3
11 12 14
PH
ALM
PWR
TS
ALM
Thermistor &
3P-Sequence,
Loss Ry
TEST/
RESET
PT1
PWR
TS
ALM
Thermistor Ry
TEST/
RESET
TS1 K8AKK8AK
22.522.5 100
90
5
72
K8AK-TS1
K8AK-PT1
K8AK-TS1 K8AK-PT1
K8AK-TS/-PT
7
Checking Operation
PTC Thermistor Input Operation
Operating Value
The input resistance gradually increases from around
1 kΩ. The operating value is the input value for which
the alarm indicator (TS_ALM) lights. The contact
outputs switch simultaneously so that you can confirm
operation.
Note: Refer to the timing charts for the operating methods for
reference.
Can phase loss be detected on the load side?
In principle, phase loss cannot be detected on the load side
because the K8AK-PT1 measures three-phase voltage to
determine phase loss.
Is it possible to detect phase losses for motor loads while
the motor is operating?
Phase loss can be detected while the motor is operating.
However, the detection conditions depend on the load
conditions that are shown in the following figure. Understand
these characteristics when using this feature.
Normally, three-phase motors will continue to rotate even if
one phase is open. The three-phase voltage will be induced
at the motor terminals. The diagram shows voltage induction
at the motor terminals when phase R has been lost with a
load applied to a three-phase motor. The horizontal axis
shows the motor load as a percentage of the rated load, and
the vertical axis shows voltage as a percentage of the rated
voltage. The solid line in the graph shows the voltage that is
induced at the motor terminals when a phase loss occurs
while the motor is operating under various loads. The figure
below shows how a phase loss that occurs while the motor is
operating causes an imbalance in the voltage across each
motor terminal. The K8AK-PT1 detects phase loss when the
motor is operating when the voltage is unbalanced.
(Detection occurs when the imbalance is 80% of the
maximum phase). The K8AK-PT1 cannot detect phase loss
with light motor loads because the voltage imbalance is too
small. The detectable range is shown by the diagonal lines.
Characteristic Curve Diagram
Note: For phase loss of phase R. VST, VTR, and VRS indicate the motor
terminal voltage at phase loss.
Questions and Answers
Q
Q
Q
100
95
90
85
80
75
70
65
60
55
50
45
10 0 20 30 40 50 60 70 80 90
100 110
VST
VTR
VRS
Note: This characteristic curve shows the approximate
values only.
Voltage (as a percentage of rated voltage)
Motor load (as a percentage of rated load)
Detectable
area
K8AK-TS/-PT
8
Safety Precautions
Be sure to read the precautions for all models in the website at the following URL: http://www.ia.omron.com/.
Warning Indications
Meaning of Product Safety Symbols
Electrical shock may occasionally cause serious injury.
Confirm that the input voltage is OFF before starting any
wiring work and wire all connections correctly.
Electrical shock may cause minor injury.
Do not touch terminals while electricity is being supplied.
There is a risk of minor electrical shock, fire, or device failure.
Do not allow any pieces of metal, conductors, or cutting chips
that occur during the installation process to enter the product.
Explosions may cause minor injuries. Do not use the product
in locations with inflammable or explosive gases.
There is a risk of minor electrical shock, fire, or device failure.
Do not disassemble, modify, repair, or touch the inside of the
product.
Loose screws may cause fires. Tighten terminal screws to the
specified torque of 0.49 to 0.59 N·m.
Use of excessive torque may damage the terminal screws.
Tighten terminal screws to the specified torque of 0.49 to
0.59 N·m.
Use of the product beyond its life may result in contact welding
or burning. Make sure to consider the actual operating
conditions and use the product within its rated load and
electrical life count. The life of the output relay varies
significantly with the switching capacity and switching
conditions.
WARNING
Indicates a potentially hazardous situation
which, if not avoided, will result in minor or
moderate injury, or may result in serious
injury or death. Additionally there may be
significant property damage.
CAUTION Indicates a potentially hazardous situation
which, if not avoided, may result in minor or
moderate injury or in property damage.
Precautions for Safe
Use
Supplementary comments on what to do or
avoid doing, to use the product safely.
Precautions for
Correct Use
Supplementary comments on what to do or
avoid doing, to prevent failure to operate,
malfunction, or undesirable effects on
product performance.
Used to warn of the risk of electric shock under
specific conditions.
Used for general prohibitions for which there is no
specific symbol.
Used to indicate prohibition when there is a risk of
minor injury from electrical shock or other source if
the product is disassembled.
Used for general mandatory action precautions for
which there is no specified symbol.
WARNING
CAUTION
K8AK-TS/-PT
9
1. Do not use or store the product in the following locations.
•Locations subject to water or oil
•Outdoor locations or under direct sunlight
•Locations subject to dust or corrosive gases (particularly
sulfurizing gases, ammonia, etc.)
•Locations subject to rapid temperature changes
•Locations prone to icing and dew condensation
•Locations subject to excessive vibration or shock
•Locations subject to wind and rain
•Locations subject to static electricity and noise
•Habitats of insects or small animals
2. Use and store the product in a location where the ambient
temperature and humidity are within the specified ranges. If
applicable, provide forced cooling.
3. Mount the product in the correct direction.
4. Check terminal polarity when wiring and wire all connections
correctly. The power supply terminals do not have polarity.
5. Do not wire the input and output terminals incorrectly.
6. Make sure the power supply voltage and loads are within the
specifications and ratings for the product.
7. Make sure the crimp terminals for wiring are of the specified size.
8. Do not connect anything to terminals that are not being used.
9. Use a power supply that will reach the rated voltage within 1
second after the power is turned ON.
10.Keep wiring separate from high voltages and power lines that
draw large currents.
Do not place product wiring in parallel with or in the same path as
high-voltage or high-current lines.
11.Do not install the product near equipment that generates high
frequencies or surges.
12.The product may cause incoming radio wave interference. Do not
use the product near radio wave receivers.
13.Install an external switch or circuit breaker and label it clearly so
that the operator can quickly turn OFF the power supply.
14.Make sure the indicators operate correctly. Depending on the
application environment, the indicators may deteriorate
prematurely and become difficult to see.
15.Do not use the product if it is accidentally dropped. The internal
components may be damaged.
16.Be sure you understand the contents of this catalog and handle
the product according to the instructions provided.
17.Do not install the product in any way that would place a load on it.
18.When discarding the product, properly dispose of it as industrial
waste.
19.When using the product, remember that the power supply
terminals carry a high voltage.
20.The product must be handled only by trained electrician.
21.Prior to operation, check the wiring before you supply power to
the product.
22.Do not install the product immediately next to heat sources.
23.Perform periodic maintenance.
Observe the following operating
methods to prevent failure and
malfunction.
1. Use the power supply voltage, input power, and other power
supplies and converters with suitable capacities and rated
outputs.
2. When cleaning the product, do not use thinners or solvents. Use
commercial alcohol.
3. The distortion in the input waveform must be 30% max. If the
input waveform is distorted beyond this level, it may cause
unnecessary operation.
4. The product cannot be used for thyristor control or on the
secondary side of an inverter. To use the product on the
secondary side of an inverter, install a noise filter on the primary
side of the inverter.
Mounting and Removing
•Mounting to DIN Track
1. Catch the upper hook on the DIN Track.
2. Push the product onto the Track until the hooks lock into place.
•Removing from the DIN Track
Pull down on the bottom hook with a flat-blade screwdriver and lift
up on the product.
Precautions for Safe Use Precautions for Correct Use
AB
PFP-100N (100 cm)
PFP-50N (50 cm)
Applicable DIN Tracks:
MEMO
10
Terms and Conditions Agreement
Read and understand this catalog.
Please read and understand this catalog before purchasing the products. Please consult your OMRON representative if you have
any questions or comments.
Warranties.
(a) Exclusive Warranty. Omron’s exclusive warranty is that the Products will be free from defects in materials and workmanship
for a period of twelve months from the date of sale by Omron (or such other period expressed in writing
by Omron). Omron disclaims all other warranties, express or implied.
(b) Limitations. OMRON MAKES NO WARRANTY OR REPRESENTATION, EXPRESS OR IMPLIED, ABOUT
NON-INFRINGEMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OF THE
PRODUCTS. BUYER ACKNOWLEDGES THAT IT ALONE HAS DETERMINED THAT THE PRODUCTS WILL
SUITABLY MEET THE REQUIREMENTS OF THEIR INTENDED USE.
Omron further disclaims all warranties and responsibility of any type for claims or expenses based on infringement by the Products
or otherwise of any intellectual property right. (c) Buyer Remedy. Omron’s sole obligation hereunder shall be, at Omron’s election,
to (i) replace (in the form originally shipped with Buyer responsible for labor charges for removal or replacement thereof) the
non-complying Product, (ii) repair the non-complying Product, or (iii) repay or credit Buyer an amount equal to the purchase price
of the non-complying Product; provided that in no event shall Omron be responsible for warranty, repair, indemnity or any other
claims or expenses regarding the Products unless Omron’s analysis confirms that the Products were properly handled, stored,
installed and maintained and not subject to contamination, abuse, misuse or inappropriate modification. Return of any Products by
Buyer must be approved in writing by Omron before shipment. Omron Companies shall not be liable for the suitability or
unsuitability or the results from the use of Products in combination with any electrical or electronic components, circuits, system
assemblies or any other materials or substances or environments. Any advice, recommendations or information given orally or in
writing, are not to be construed as an amendment or addition to the above warranty.
See http://www.omron.com/global/ or contact your Omron representative for published information.
Limitation on Liability; Etc.
OMRON COMPANIES SHALL NOT BE LIABLE FOR SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
LOSS OF PROFITS OR PRODUCTION OR COMMERCIAL LOSS IN ANY WAY CONNECTED WITH THE PRODUCTS,
WHETHER SUCH CLAIM IS BASED IN CONTRACT, WARRANTY, NEGLIGENCE OR STRICT LIABILITY.
Further, in no event shall liability of Omron Companies exceed the individual price of the Product on which liability is asserted.
Suitability of Use.
Omron Companies shall not be responsible for conformity with any standards, codes or regulations which apply to the
combination of the Product in the Buyer’s application or use of the Product. At Buyer’s request, Omron will provide applicable
third party certification documents identifying ratings and limitations of use which apply to the Product. This information by itself is
not sufficient for a complete determination of the suitability of the Product in combination with the end product, machine, system,
or other application or use. Buyer shall be solely responsible for determining appropriateness of the particular Product with
respect to Buyer’s application, product or system. Buyer shall take application responsibility in all cases.
NEVER USE THE PRODUCT FOR AN APPLICATION INVOLVING SERIOUS RISK TO LIFE OR PROPERTY OR IN LARGE
QUANTITIES WITHOUT ENSURING THAT THE SYSTEM AS A WHOLE HAS BEEN DESIGNED TO ADDRESS THE RISKS,
AND THAT THE OMRON PRODUCT(S) IS PROPERLY RATED AND INSTALLED FOR THE INTENDED USE WITHIN THE
OVERALL EQUIPMENT OR SYSTEM.
Programmable Products.
Omron Companies shall not be responsible for the user’s programming of a programmable Product, or any consequence thereof.
Performance Data.
Data presented in Omron Company websites, catalogs and other materials is provided as a guide for the user in determining
suitability and does not constitute a warranty. It may represent the result of Omron’s test conditions, and the user must correlate it
to actual application requirements. Actual performance is subject to the Omron’s Warranty and Limitations of Liability.
Change in Specifications.
Product specifications and accessories may be changed at any time based on improvements and other reasons. It is our practice
to change part numbers when published ratings or features are changed, or when significant construction changes are made.
However, some specifications of the Product may be changed without any notice. When in doubt, special part numbers may be
assigned to fix or establish key specifications for your application. Please consult with your Omron’s representative at any time to
confirm actual specifications of purchased Product.
Errors and Omissions.
Information presented by Omron Companies has been checked and is believed to be accurate; however, no responsibility is
assumed for clerical, typographical or proofreading errors or omissions.
0513
Authorized Distributor:
In the interest of product improvement,
specifications are subject to change without notice.
Cat. No. N189-E1-01 0314 (0314)
© OMRON Corporation 2014 All Rights Reserved.
OMRON Corporation Industrial Automation Company
OMRON ELECTRONICS LLC
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IL 60173-5302 U.S.A.
Tel: (1) 847-843-7900/Fax: (1) 847-843-7787
Regional Headquarters
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Alexandra Technopark,
Singapore 119967
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200 Yin Cheng Zhong Road,
PuDong New Area, Shanghai, 200120, China CSM_1_1_0314
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