Datasheet

34
Recovery time
After tripping due to overload, the thermal overload relays require
some time until the bimetal strips have cooled down. The device
can only be reset after the bimetal strips have cooled down. This
time (recovery time) depends on the tripping characteristics and
strength of the tripping current. The recovery time allows the load
to cool down after tripping due to overload.
Benefits and features
High performance
• In-built single phasing protection
In case of phase loss the current through the other two
windings increases by 1.732 times the rated current of the
motor. The current now flows only through the 2 bimetallic
strips which should produce the required force on the tripping
mechanism. This needs higher currents for longer time. As
current is not too high so the relay might take higher time to
trip. This can cause damage to the motor. Similar condition
happens in case of phase unbalance. To take care of these
conditions our birelays are constructed such that they offer a
built-in single phasing protection using differential slider
principle.
• Temperature compensation
The temperature compensation feature reduces the effect of
the ambient temperature on the tripping behavior. This ensures
the minimum tripping current lies within the specified range
for -25 to 55° C. For this purpose the relays are temperature
compensated between service temperatures of -25° C to
+55° C.
User friendliness and safety
• SIGUT termination Technique
– Shrouded auxiliary terminals
Increases safety, as they protect against accidental contact
with live parts.
– Funnel shaped cable entries
Reduce wiring time by facilitating quick location of the
connecting wire.
– Cable end-stop
They decide the insertion depth of the connective wire. As
the wire cannot now protrude into the relay housing, it does
not hamper the movement of the auxiliary contacts. Since
the insertion depth is predetermined, insulation of the cable
can be cut accordingly and the possibility of insulation
getting inadvertently caught under the terminal, is avoided.
– Captive Screws
This feature prevents the screws from falling down thereby
facilitates the wiring. Hence, the relays are delivered with
untightened terminals. This eliminates the operation of
untightening terminals before wiring.
– Lug less termination
This feature helps in reducing the termination time.
– Screw-driver guides reduce wiring time as they allow the
use of power screw-drivers.
Flexibility
• Potential free Auxiliary Contacts
Potential free 1NO + 1NC contact arrangement is provided as a
standard feature. The 1NC contact is used in the control circuit
of the contactor for disconnecting the motor in case of
overload, whereas the 1NO contact can be used for various
applications such as indication.
• Mounting
3UA5: suitable for direct mounting or independent mounting
(with the help of independent mounting accessory)
3UA6 and 3UC5/6: suitable for Independent mounting.