49
Thermal overload relay Others
Thermal overload relay
operates.
Miss-selection of thermal
overload relay current
Corrosion of heater due to
oxidation
Operating failure of thermal
overload relay
Fusing of heater
Wiring failure of operating
circuit
Installing method of power
condenser
Bounce of operating switch
Operating and contact failure
of operating switch
Miss-application of operating
circuit voltage
Error in mounting condition
Miss-selection of capacity
Operating (open/close)
frequency is too high.
Miss-selection of protective
structure from dust or gas.
Short circuit or grounding
of the load side
Miss-connection for reversible
type
Miss-connection of wire for
coil tap
The starting time of load is
long.
Vibration and shock are great.
Wiring failure
Ambient temperature is too
high.
Ambient temperature is too
low .
Overload of machine
short circuit trouble of
wiring
Reset it.
Set the current value with load current, or replace
thermal overload relay.
Replace thermal overload relay, and moreover, use
protective box suitable for environment.
Replace thermal overload relay.
Remove the cause and replace thermal overload
relay. Thermal overload relay dose not protect
large current like short circuit.
Check the circuit and match it with connection
diagram. Concurrently, check grounding and dis-
connection of circuit, or tightening of connection
terminals.
Connect it to motor terminals or load terminals of
starter. (see page 47)
Repair or replace the operating switch. (push-
button switch, float-free switch, limit switch, etc.)
Check the limit switch, pressure switch, etc.
Replace parts. (coil)
Correctly mount it to the vertical face (see page 36)
Select the suitable starter.
Re-examine the application. In case of plugging and
inching, it is necessary to limit the rated capacity.
Use one with protective structure suitable for
environment.
Remove the cause and provide a reliable, protective
device against short circuit.
Change it to a correct wiring.
Replace coil or change the connection of wire for
coil tap.
Change to thermal overload relay with saturation
reactor; there is another method to use timer.
(see page 31)
Examine and change the mounting method and
place of starter.
Check the circuit and match it with the connection
diagram. At the same time, check the grounding
and disconnection of circuit and tightening of
connection terminals.
Consult with our company's agent, sales store and
service station about the troubles, and change the
installation place of thermal overload relay or
replace it with one with appropriate characteristics.
Taking into consideration the sequence of overload →
operation of thermal overload relay → incapability of
closing, investigate the cause and remove it, then
reset the relay.
Eliminate the cause and install a protective device
against short circuit, for instance, fuse-free breaker
and the like.
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