In the direct-online starter, NO-VOLT release is to
Right Answer is:
Safeguard the motor against the failure of the supply
When motors use a starter which is used to connect the stator directly to the supply lines without any reduction in voltage. It is known as the direct online starter. The direct-online starter, NO-VOLT release is to Safeguard the motor against the failure of the supply.
The direct online starter in the motor does not reduce the applied voltage, it is used because it protects the motor from various severe abnormal conditions like overloading, low voltage, single Chasing, etc.
The NO contact is normally open and NC is normally closed. At the start, NO is push for fraction of a second due to which coil gets energized and attracts the contractor. So stators directly get supply. The additional contact provided ensures that as long as supply is ON, the coil gets supply and keeps the contactor in ON position. When NC is pressed, the coil circuit gets opened due to which coil gets de-energized and the motor gets switched OFF from the supply.
Under overload conditions, the current drawn by the motor increases due to which there is excessive heat produced, which increases temperature beyond the limit. Thermal relays go opened due to high temperature, protecting the motor from overload conditions.
Hence from the above, it is clear that No Volt Coil ensures that whenever supply resumes after switching off or supply failure, the motor does not start on its own, but starts only after the user starts it, and that too through current limiting resistors. When the supply voltage is below 85% of its rated voltage or it suddenly fails, the no volt-coil becomes demagnetized