how to use contactor

  Appeared here is a contactor for a three-stage electric engine, introduced on a board as a component of an electrical control framework at a civil water treatment plant:

Three-stage, 480 volt AC control comes into the three regularly open contacts at the highest point of the contactor by means of screw terminals marked "L1," "L2," and "L3" (The "L2" terminal is holed up behind a square-molded "snubber" circuit associated over the contactor's loop terminals). Energy to the engine leaves the over-burden radiator get together at the base of this gadget through screw terminals marked "T1," "T2," and "T3."

 The over-burden warmer units themselves are dark, square-formed pieces with the name "W34," demonstrating a specific warm reaction for a specific drive and temperature rating of electric engine. In the event that an electric engine of varying force as well as temperature appraisals were to be substituted for the one quickly in administration, the over-burden warmer units would need to be supplanted with units having a warm reaction reasonable for the new engine. The engine maker can give data on the suitable warmer units to utilize.

A white pushbutton situated between the "T1" and "T2" line radiators serves as an approach to physically re-set the ordinarily shut change contact back to its ordinary state subsequent to having been stumbled by exorbitant warmer temperature. Wire associations with the "over-burden" switch contact might be seen at the lower-right of the photo, almost a mark perusing "NC" (ordinarily shut). On this specific over-burden unit, a little "window" with the name "Stumbled" demonstrates a stumbled condition by method for a shaded banner. In this photo, there is no "stumbled" condition, and the pointer seems clear.

As a reference, radiator components might be utilized as a rough current shunt resistor for figuring out if or not an engine is drawing current when the contactor is shut. There might be times when you're taking a shot at an engine control circuit, where the contactor is situated far from the engine itself. How would you know whether the engine is expending power when the contactor loop is stimulated and the armature has been pulled in? In the event that the engine's windings are scorched open, you could send voltage to the engine through the contactor contacts, yet at the same time have zero current, and accordingly no movement from the engine shaft. On the off chance that a clasp on ammeter isn't accessible to quantify line current, you can take your multimeter and measure millivoltage over every warmer component: if the current is zero, the voltage over the radiator will be zero (unless the radiator component itself is open, in which case the voltage crosswise over it will be extensive); if there is present heading off to the engine through that period of the contactor, you will read an unequivocal millivoltage over that warmer: