Low Voltage Switch Gear
Appendix
81
Low Voltage Switch Gear
Appendix
Precautions
■
Notice
Use under rated condition, otherwise contactors will not only cause
malfunction, but also cause a fire or damage the contactor.
Life period of contactor depends on the operating application. Please
check the electrical life under real application in advance.
If you continue to use malfunctioning contactor, a fire or breakdown
may occur.
Do not miss-wire or miss-charge the power supply, otherwise the
contactor does not work correctly.
Do not operate in places with explosive or flammable gas, otherwise
a fire or explosion may occur by arc or heating from contactor.
Make sure to use the circuit well considered about safety, in case
there is any possibility to cause secondary disaster by contact trou-
ble (welding, faulty contact).
Do not supply short-circuit current to electromagnetic switch (contac-
tor with thermal relay). Doing so may result failure in heater of ther-
mal relay. Please use short-circuit protection like fuse or protective
circuit breaker.
Do not use a contactor or thermal relay which has been dropped or
dismantled. Doing so may cause malfunction or a fire.
Make sure to shut off power supply to contactors before wiring or
replacing.
Do not operate the actuator of a contactor manually. Doing so may
cause contact welding by chattering or burn out by arc.
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Correct use
General use
Unexpected malfunction may occur in real application. Please carry
out as many tests as possible.
Ratings in this catalogue measured under the condition according to
IEC unless otherwise specified. In cases of check by real application,
please carry out the test under the same condition as expected in the
actual application.
Selection
Coil specification
Please select suitable coil to circuit design, otherwise malfunction
may occur or coil may have a burn out by overvoltage etc.
Type
Please check contact ratings, switching capacity, thermal character-
istics etc. when selecting product type.
Thermal relay
Motor current differs by supplier, type, number of poles, frequency.
Please confirm operational current level.
Coil surge suppressor
Coil surge suppressor type should be selected by contactor type,
auxiliary relay type and applied voltage. Make sure to use defined
each contactor.
In case of installing coil surge suppressor, please check the actual
circuit because the release time will be delayed.
Electrical life expectancy
Electrical life expectancy tests in this catalogue are based on IEC.
Circuit design
Supplied voltage waveform for input
Make sure to apply and remove the voltage instantly. Do not use
under the condition that the coil voltage waveform increases or
decreases gradually.
In case of DC contactor use (input voltage
ripple)
Please use DC contactor input voltage with a ripple ratio less than
5%. Excessive ripple (pulsating current) may cause contact welding.
Fluctuation of input voltage
Make sure to supply sufficient voltage to actuate contactors properly.
Continuous supply of insufficient voltage results in excessive heating
and may cause burn out of coil.
Maximum applied voltage
Do not supply the voltage over the maximum rated voltage, otherwise
burn out or insulation failure may occur.
The temperature inside control panel has much influence to the coil
temperature, so make sure not to exceed the specified value in the
catalogue.
Basically rated voltage should be supplied to coil. To supply higher
voltage than rated would result in shorter electrical life, even if it is
lower than the maximum rated voltage.
Reverse
Make sure to use reversible contactors for reverse operation.
Make sure to use interlock device in reverse operation by two contac-
tors, otherwise short circuit current may burn out or give damage to
contactors and motors.
Unless otherwise stated in the catalogue,
modifications, especially those of stated values,
sizes and weights are subject to alternation.
Diagrams and tables are subject to alternation and
not to be regarded as binding drawings.
