Need help deciphering the side label of a contactor or relay?


Today we are going to help decipher all the information that can be found on the side label on any contactor or relay.  To be hones there is a ton of information on there and most of it are electrical ratings.  We will explain each important section along with providing the common misconceptions as to what this information actual relates to.

1. IEC/EN and VDE - These are electrical category ratings used for Europe, the UK and North America.  They simply denote what type of electrical product it is and are not specific to any manufacturer or individual part.  Every contactor made on the market today with have a IEC/EN code of 60947, no matter if it is manufactured by Schneider, Eaton, Allen Bradley or Siemens.
  **Common misconception - despite being at the top of the label, this is not the part number.  It will not be specific to any part and does not help in determining what contactor is needed

2. Ith=32A - this is the thermal current rating for the contactor and that it can switch loads up to 32 AMPS AC-1.  It is important to note that this is the AC-1 rating, not the more common UL AC-3 rating.  AC-1 ratings are used for resistive loads.
  **Common misconception - This is not necessarily the AMP rating of the contactor.  The label to the left is for a 32 AMP AC-1, 18 AMP AC-3 and in 99% of all applications you will want to go by the AC-3 rating

3. kW and H.P. ratings - This charts shows the different kilowatt and horsepower ratings at different voltages for 3 Phase applications.  For example, this contactor is rated 5.5 H.P. @ 230 volt and 10 H.P. at 440 volt 3 Phase.
  **Common misconception - This is just a table for kW and H.P. ratings and has nothing to do with the coil or control voltage

4.  32A 600V - This rating is for the base mounted auxiliary contact block (usually terminals numbers 13/14 for normally open contacts and 21/22 for normally closed contacts) and has no bearing on the AMP rating or voltage of the contactor.  This is the maximum current that can be passed through this contact
  **Common misconception - This is not the AMP rating or voltage for the contactor, just the auxiliary contact that is on the contactor

5. H.P. ratings - This is the chart for single and three phase horsepower ratings for this contactor.  For example, this contactor is rated for 3 H.P. @ 230 volt single phase and it is also rated for 10 H.P. @ 460 volt three phase. 
  **Common misconception - these are just the H.P. ratings and have nothing to do with the line or control (coil) voltages for this contactor

What is electrical phase loss?

Phase loss is simple: the loss of a phase (or pole, leg) in a 3 phase system often cause by a blown fuse, overload relay malfunction, old worn contacts or simply mechanical failure.  This resulting loss causes excessive AMP draw on the remaining phases which can quickly cause damage to your motor windings.  For example, [...]

Read More »

The importance of tightening torque on electrical installations

Often overlooked during the installation or replacement of electrical parts is the importance of tightening the wires to the terminals with the correct amount of torque.  While the focus may be on the wiring diagram and ensuring the correct connections, correctly tightening the terminals is just as important to ensure a safe and secure installation.  [...]

Read More »

How to determine if you have a bad contactor coil

Many times when we have a contactor in an application and it is not pulling in (turning on), we assume the whole contactor or just the coil is bad.  While this may be the case, it is important to ensure the contactor is receiving the necessary voltage to actuate the coil.  Many times the contactor [...]

Read More »

What is the difference between Class ratings on overload relays?

You may have sent overload relays with different Class ratings.  Class 10 and Class 20 tend to be the most common there is also a Class 5 rating and a Class 30.  So what does the difference mean? Simply put the Class rating specifies in what amount of time the overload will trip after it [...]

Read More »

The difference between a coil (control) voltage and a line voltage

When choosing the appropriate coil voltage for your contactor, it is important not to confuse the coil (control) voltage with the line voltage. The difference between the two is simple. The line voltage can be measured through the power poles of the contactor, and for 3 pole contactors that is the L1, L2 [...]

Read More »

AC-1 Versus AC-3 Electrical AMP Ratings

This week we want to discuss the difference between the standard AMP ratings for IEC and UL contactors. First we will simply define the two main types of ratings that are used for contactors. First is the most common AC-3 rating. This rating is used most often as the benchmark AMP rating [...]

Read More »

New Launches March 8th, 2017!!!

We imagine some bumps along the way but our new interface will make it easier to find the parts you need, check availability and order seamlessly online.

Read More »