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K2CM

15

Maintenance and Inspection

The K2CM Motor Protective Relay offers very stable characteristics.
To maintain these characteristics for a long time, the following
inspections are recommended.

Daily Inspection

The purpose of daily inspection is to discover causes of failure before
using the Motor Protective Relay. This inspection depends somewhat
on the perception of the operator as it includes visual checking, etc.

Periodic Inspection

This inspection is performed by turning OFF the power at regular
intervals to check the aging caused by long-time operation. It is rec-
ommended that periodic inspection is performed once a year.

Motor Protective Relay

External Rectifier

Check for adhesion of dust and foreign objects, damage to wirings by
burning, and loosening of mounting screws.

What is the VA consumption of the CT section?

The consumption is 0.4 VA/phase max. for any CT section.

What action is required if an inverter circuit is used?

As shown in the following figure, insert the K2CM and turn 
OFF the reverse-phase switch before using the K2CM. 

Always insert the K2CM on the secondary side (load side) 
of the inverter.  

Error may occur in the operating values depending on the 
inverter specifications and settings. Set the values after 
performing tests and confirming operation.

The current waveform on the inverter power supply side is 
distorted, so the K2CM may malfunction.

The inverter load side contains a large high-frequency 
component, so the K2CM may malfunction due to phase 
reversal.

Depending on the specifications and settings of the 
inverter, overloads and open phases may also cause the 
K2CM to malfunction.

What action is required if single phase is used?

The following describes the operating procedure for using a 
single phase with the K2CM.

Connection Method
Pass wires through any two of the three holes on the 
K2CM.

If a single phase is used, set the open-phase and reverse-
phase switch to OFF. Make the overload settings so that 
they match the motor current.

Do not apply control power supply voltage between the V-
W terminals if a model with voltage reverse-phase 
detection is used.

Classification

Inspection items

Connections

Loosening, damage, and dust collection at 
screw terminals, damage to wiring insulation 
sheaths, excessive force applied on wirings, 
adhesion of foreign objects to terminal 
screws

Motor Protective Relay Adhesion of foreign objects and dust to the 

operation panel, shift of set value, indication 
status of operation indicators and trip indica-
tor, presence/absence of front cover, loos-
ening of screws combining rectifier and 
control circuits, deformation of case, abnor-
mal temperature on housing surface

External rectifier

Loosing of terminals, unusual odor, discolor-
ation of surface

Classification

Inspection item

Construction

Adhesion of dust and foreign objects to 
terminals, cracks in insulators around 
terminal block, burn damage to wirings, 
damage to setting knobs, selector 
switches, test button, and reset button, 
damage to insulators of solderless ter-
minals, rust and discoloration of screw 
terminals

Operating characteristics

Refer to 

Testing Method

.

Insulation resistance

Between terminals and mounting panel

Operation check with test 
button

Checking of operating time, operation 
indicators, and trip indicator

 Mounting

location

Element

Inverter power 

supply

Inverter load

Overcurrent

NG

Conditionally OK

Open-phase

NG

Conditionally OK

Reverse-phase

NG

NG

Q & A

Q

Q

M

Motor

K2CM

In

v

erter

Q

M

Motor

K2CM

In the interest of product improvement, specifications are subject to change without notice.

ALL DIMENSIONS SHOWN ARE IN MILLIMETERS.

To convert millimeters into inches, multiply by 0.03937. To convert grams into ounces, multiply by 0.03527.

Summary of Contents for K2CM Series

Page 1: ...ng the K2CM Model Number Structure Model Number Legend 1 Model K2CM Motor relay 2 Mounting style None Surface mounting integrated type 3 Operating time characteristics None Inverse type Q Instantaneou...

Page 2: ...AC 2 A 440 VAC 1 A 110 VDC 0 2 A 220 VDC 0 1 A Contact form of output contact Current reverse phase detection models SPST NO SPST NC Voltage reverse phase detection models SPDT Operating current range...

Page 3: ...Current reverse phase detection models 6 000 V between current carrying terminals and mounting panel 4 500 V between current carrying terminals and between control power supply terminals Waveform 1 2...

Page 4: ...Manual Operation High voltage Circuit Note Connect the phase advancing capacitor on the power supply side of the Motor Protective Relay as shown in the above dia grams Ta Tc Tb U V W Output contacts...

Page 5: ...t High capacity Motor Automatic Operation Low voltage Circuit Manual Operation High voltage Circuit S1 C2 b2 a1 c1 S2 Output contacts NO and NC Control power supply R S T BZ R U A 1 S V B 2 T W C 3 a1...

Page 6: ...ens of seconds to settle to the rated current This time varies largely depending on type of motor and the nature of motor load wt There fore it is necessary to obtain the motor s starting time for ope...

Page 7: ...required for the detection of inter nal open phases in delta connected motors Consult your OMRON representative before using this method When a transformer is con nected as a load the harmonics increa...

Page 8: ...n 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 N...

Page 9: ...is made at the load side far from the current transformer and the motor rotates in the re verse direction the K2CM does not detect the reverse phase Reverse detectable Range The OR phase circuit in th...

Page 10: ...aracteristics for Inverse Type Overload Operating Time Characteristics for Instantaneous Type 2 0 1 0 0 100 200 300 400 500 600 700 This graph shows the behavior when the current changes from 100 of t...

Page 11: ...ive motor full load characteristics of 200 VAC 4 pole totally enclosed Note When using a large capacity or high voltage motor whose capacity is 45 kW or more calculate the rated current alternating cu...

Page 12: ...the input phases for the cur rent transformer 2 Turn ON SW1 and SW2 Gradually increase the current by adjusting the voltage regulator 3 Confirm that the K2CM operates at a current no greater than 85 o...

Page 13: ...3 Using the voltage regulator abruptly increase the current to 140 of the set current value Confirm that the K2CM performs the instantaneous operation 4 Turn OFF SW1 and SW2 Open phase 1 Open disconn...

Page 14: ...ection of a high voltage motor or low voltage high capacity motor use an external rectifier that does not saturate at currents up to 600 of the rated motor current and thus permits a large overcurrent...

Page 15: ...ase with the K2CM Connection Method Pass wires through any two of the three holes on the K2CM If a single phase is used set the open phase and reverse phase switch to OFF Make the overload settings so...

Page 16: ...ther 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...

Page 17: ...2CM 1LA K2CM 1LS K2CM 1M K2CM 1MA K2CM 2H K2CM 2HA K2CM 2L K2CM 2LA K2CM 2LS K2CM 2M K2CM 2MA K2CM 4H K2CM 4HA K2CM 4L K2CM 4LA K2CM 4M K2CM 4MA K2CM Q1H K2CM Q1HA K2CM Q1L K2CM Q1LA K2CM Q1LS K2CM Q1...

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