hold on contacts

[donowgh]

Just wondering if anyone could explain how hold on contacts work

 

[big bobbyx10]

Just wondering if anyone could explain how hold on contacts work

As long as you have a control voltage, it energizes a coil ,which in turn closes and makes the contact, magnetics, if you loose your voltage,circuit will open and contacts drop out.

 

[jpmiff]

Hi

hold on contacts are latching contacts (NO) which are in on the relay/contactor paralled with a romote start contact (NO), when the start is pressed this energises the relay/contactor coil, closing the latching contacts keeping the relay/contactor coil energised until the stop contact (NC) is operated breaking the latch circuit.

try google to find a circuit diagram

 

[donowgh]

what about when you have a motor and you want to start it with a push button it starts when you push it but when you stop pushing it it stops how do you get to stay on

 

[bomjac]

The purpose of the hold in contact is to provide a current path through the relay coil when you release the start button. That is why it is wired in parallel with the start. Similarly, the stop is wired in series to break the relay circuit and hence stop the motor.

Complete online tutorial on Basics of Control Comonents

Diagram courtesy of Siemens on This Web Page.

In general, additional stop buttons are always wired in series at the start of the control circuit, additional start buttons in parallel with the hold in contact. Follow the link on the 2nd line for a step by step guide from Siemens online.

 

[jpmiff]

with a latching circuit