- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
When the OL is tripped on a starter, what state do the aux contacts on the OL relay go to?
Starter OL Contact States
- Thread starter George Stolz
- Start date
- Status
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
They will change state.
Most IEC overloads the aux contact is a N.O. that will close when the OL trips. I think you can usually buy a NC contact to add to it.
NEMA stuff you can buy with either a NO or NC aux contact.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Most standard contacts simply change state.
In general every OL relay has at least 1 contact which is consider Normally Closed (it is closed when there is no overload). This contact opens on an OL trip thus breaking the coil circuit.
IEC overload relays almost always come with an additional contact which is Normaly Open and then closes when a trip occurs, this is often called an alarm contact. This second contact is usually an adder for NEMA starters. It is typical for this contact to share a common terminal with the NC contact.
Of course there are exceptions such as (2) open contacts or contacts with isolated terminals.
In general every OL relay has at least 1 contact which is consider Normally Closed (it is closed when there is no overload). This contact opens on an OL trip thus breaking the coil circuit.
IEC overload relays almost always come with an additional contact which is Normaly Open and then closes when a trip occurs, this is often called an alarm contact. This second contact is usually an adder for NEMA starters. It is typical for this contact to share a common terminal with the NC contact.
Of course there are exceptions such as (2) open contacts or contacts with isolated terminals.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Thanks, I thought the book was wrong.
- Status