Tim Ganz
Member
When using overloads I am familiar with the old heater type and those would open the overloads contact points and prevent power flow if I remember right? I was always taught that the neutral of the contactor coil should run through the overload aux contacts so the contactor coil will drop out when the overload kicks.
Now here on a new job they have the electronic type of overload and the other day one was found where a motor winding opened and did not trip the overload but tripped stuff upstream.
The guy here found that the contactor coil cam from the plc and did not go through the overload aux contacts but the aux contacts are a loop to a plc input that shows the overload tripped on the HMI screen.
Our electrician said that on electronic overloads that when they trip they don't break power on the 3 power leads they just open the aux contacts and that if the neutral or power wire for the coil for the contactor does not go through those aux contacts then the motor will never stop.
Is this true? Do electronic overloads not break 3 phase power in themselves? They only change the aux contact state?
Now here on a new job they have the electronic type of overload and the other day one was found where a motor winding opened and did not trip the overload but tripped stuff upstream.
The guy here found that the contactor coil cam from the plc and did not go through the overload aux contacts but the aux contacts are a loop to a plc input that shows the overload tripped on the HMI screen.
Our electrician said that on electronic overloads that when they trip they don't break power on the 3 power leads they just open the aux contacts and that if the neutral or power wire for the coil for the contactor does not go through those aux contacts then the motor will never stop.
Is this true? Do electronic overloads not break 3 phase power in themselves? They only change the aux contact state?