|Country of Origin||Made in India|
Relay type VDG 13 is a heavily damped, frequency compensated induction disc relay with adjustable inverse time/voltage characteristic. With the Alstom Undervoltage Relay
electro-magnet deenergised, the disc contact is held in the closed position by a spiral control spring. When the rated voltage is applied to the relay coil, a torque is produced in the contact opening direction and when the applied voltage falls below the setting value, the control spring torque overcomes the driving torque and closes the contact.
Damping of the disc movement is by a removable high retentivity permanent magnet. The unique method of winding the operating coil ensures that the time/ voltage characteristics are identical on each of the voltage taps. Selection of the required voltage setting is by means of a link board which has a single insulated link.
Taps on the operating coil and a series resistance are connected to the link board and provide a constant inductance/resistance ratio on each voltage setting and frequency compensation effect is obtained by using the correct combination of coil reactance and resistance. The relay operating time can be adjusted by means of the disc backstop which is controlled by rotating a knurled moulded disc at the base of the graduated time multiplier scale.