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.

• Using a K2MR is recommended to protect the inverter

motor.

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

Inverter

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.