The way to Select and Use Contactor Overload Protectors (AUTOMATION,PLC,HMI,FACEBOOK)

The way to Select and Use Contactor Overload Protectors

          Overload protectors keep motors from burning out when under prolonged heavy loads. that would flow from to a jammed conveyor, a nasty bearing or maybe too many rapid starts or forward and reverse cycles. just about anything that would increase the winding and motor temperature. While it's typically sold as an add-on accessory, you ought to consider it indispensable and cheap insurance. And in fact -- it's required by code.

         An overload including a contactor gives you the beginnings of a real motor starter. and that they are easy to use. Here is an overload for a contactor. you only insert it on the load side of the contactor and tighten the screw clamps then set the present where you would like it to trip. The load wiring now connects here at the output of the overload. to check it, just press this button, the overload will trip its contacts, and it'll set a touch indicator during this window. To reset it, just press the blue button here.

 it is vital to know that the overload doesn't cutoff power to the motor -- it just opens and closes its own contacts. 

          for instance , this unit features a Normally Open and Normally Closed contact. Wire the normally closed contacts serial with the contactors coil to cutoff power to the motor. Wire the normally open contacts to the PLC so it can monitor the status of the overload. 

         On most overloads, you'll see an option like this where you'll set the overload handy operated, or Automatic. immediately this is often pointing to the hand operated setting and to rotate this dial to automatic you really need to put a screw driver during this little slot and break off this tiny tab. that ought to be a touch that normally you'll want to stay this in hand operated mode. That way the overload can't automatically reset itself while you're performing on the machine. If you are doing want to try to to an automatic reset, then break this tiny tab, depress the blue dial and twist it to lock it into automatic reset mode.

          Here may be a Overload. it is the same thing. You clamp it in and dial within the trip current you would like . Because the overload blocks access to the Contactors A2 terminal and therefore the aux contact, those are brought out here so you'll still access them. Also, resetting the mini-contactor may be a little different too. There are TWO hand modes and TWO automatic modes. H Mode and HAND Mode both reset the overload after it's tripped once you press this button.

          The difference is that if the overload hasn't tripped, HAND mode will toggle the overloads contacts so you'll test your systems response to an overload fault by pressing this button. That's really handy. But it could even be dangerous, so you've got H Mode which does not do anything when the overload isn't tripped. you'd use H mode if you would like to make certain the overloads contacts cannot be toggled during normal operation. In AUTO reset mode, the contactor automatically resets so pressing this button just toggles the contacts so you'll test the systems response to an overload fault. within the "A" mode, pressing the button doesn't do anything because the overload automatically resets and therefore the button doesn't have any effect on the contacts.

           Again, you'll normally want to use one among the manual reset modes and avoid using the automated reset mode so your machine doesn't start itself copy unexpectedly. Here's an overload for a contactor. Same thing. Clamp it into the contactor and dial within the current you would like it to visit . The Overload contacts on this one are up here and here's the push button . The Eaton overload may be a bit different. rather than dialing within the current you would like it to visit , you connect little heater packs here. you only select the module with the trip point you would like . Otherwise it's still an equivalent animal. Here's an overload for a bigger contactor.

           Again, it is the same thing, just bigger. Overloads also typically detect phase loss, so if one leg of your power circuit goes down, the overload will trip thereon too. 

 Does that mean you cannot use overloads on single phase motors? Not in the least -- just make certain to run one among the lines serial through two legs of the overload like this. As you'll see, these are all basically an equivalent - they only have different shapes and designs and therefore the contacts are located in several places. confine mind that while overloads AND circuit breakers and fuses are all system protection devices, they're not an equivalent thing. 

           Overloads protect the motor from prolonged heavy loads and take time to trip. Circuit breakers and fuses detect things like short circuits and react very quickly. you actually need both to properly protect your system.