Triangle connection of the motor Why use a phase-protected thermal relay?
Because when the three-phase motor connected to a phase of a loose or a fuse fuse, resulting in the lack of motor operation, which is three-phase asynchronous motor burned one of the main reasons. After the phase, if the load does not change, the current in the winding will increase, will make the motor burned.
Make protection. If the motor is △-shaped connection, the occurrence of phase failure, due to the motor phase current and line current
The current flowing through the motor winding and the proportion of the current flowing through the thermal relay are not the same, and the thermal element is connected in series with the rated current of the motor, that is, the line current,
Big. When the fault line current reaches the rated current, within the motor windings, the larger current that phase winding
The fault current will exceed the rated phase current, there is the risk of overheating. So △ connection must be used to break
Phase protection thermal rela
One of the three-phase motor wiring is broken or a fuse is broken, which is caused by three-phase asynchronous motor burned
One of the main reasons. If the thermal relay to protect the motor is Y connected, when the line occurs a phase power
, The other two-phase current will increase a lot, because the line current is equal to the phase current, the current flowing through the motor winding and flow through the thermal relay to increase the proportion of the same, so the ordinary two-phase or three-phase thermal relay
y.
