6.1 DC resistance (R) and Continuity (CTY)
Continuity is a simple test to ensure that the fixture as well as the transformer has been inserted correctly. The test parameters provided range from 10KΩ to 10MΩ, 10KΩ is generally used for speed and will test each winding and termination for a value less than 10KΩ.
Resistance is the direct current (DC) resistance offered by an inductor due to the resistance of the magnetic wire used. Resistance is the undesirable characteristic, which is the by-product of the wire or conductive material used. Resistance measurement’s are generally taken across all windings and is directly linked to the design of the transformer to carry a particular amount of current within that winding. The lower the resistance the higher the current carrying capabilities of the inductor.
R1, R2, and R3 represent the resistance of the copper wire used to wind the transformer. When current flows in the windings the resistance causes losses in the windings (I2R losses), and generates heat. In addition the winding resistances cause a voltage drop in the windings when current flows, causing the output voltage to fall with increasing load. (This effect is known as 'Regulation')
A DC resistance test used to check that each winding is terminated properly and that the correct wire gauge has been used.
This test will check for the correct wire used and of course good solder termination integrity (it does this on a winding by winding basis).
DCR is the direct current (DC) resistance offered by an inductor due to the resistance of the winding. Expressed in ohms or milliohms maximum. The lower the DCR the more current an inductor or transformer can handle.