Timing relays:Capacitor Time Limit Relay

Capacitor Time Limit Relay

Assume that a capacitor is charged by connecting it momentarily across a DC line, and then the capacitor direct current is discharged through a relay coil. The

TIMING RELAYS-0619

current induced in the coil will decay slowly, depending on the relative values of capacitance, inductance, and resistance in the discharge circuit.

If a relay coil and a, capacitor are connected parallel to a DC line (Figure 7– 12), the capacitor is charged to the value of the line voltage and a current appears in

TIMING RELAYS-0620

the coil. If the coil and capacitor combination is now removed from the line, the current in the coil will start to decrease along the curve shown in Figure 7 – 12.

If the relay is adjusted so that the armature is released at current i1, a time delay of t1 is obtained. The time delay can be increased to a value of t 2 by adjusting the relay so that the armature will not be released until the current is reduced to a value of i 2. Figure 7 – 13 shows a relay used for this type of time control.

A potentiometer is used as an adjustable resistor to vary the time. This resistance-capacitance (RC) theory is used in industrial electronic and solid-state controls also. This timer is highly accurate and is used in motor acceleration control and in many industrial processes.

Incoming search terms:

Leave a comment

Your email address will not be published. Required fields are marked *