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.
