12-02-2015, 01:07 AM
I want to preaperd to a seminar ppt on this topic,
so i want to some data here.please give me some data.
thanks
|
under frequency relay wikipedia
|
I want to preaperd to a seminar ppt on this topic,
so i want to some data here.please give me some data.
thanks
10-03-2017, 09:36 AM
Low-frequency protection relay
The low-frequency relay (Figure 4-16) is a solid state device that works to protect the load on the frequency of the event generator that falls below the preset limits. It is activated when the frequency decreases to 55 hertz for 60 hertz operation and 46 hertz for 50 hertz operation. When actuated, the contacts within the relay are approached to signal the annunciator and are opened to deenergize the generator switch (contactor), resulting in a display of the fault condition and the elimination of the generator load.
Frequency detection is performed by a tuned circuit consisting of capacitors C1 and C2 and components in the encapsulated base. Zener diodes CR1, CR2 and CR3 limit the maximum voltage to the tuned circuit. The AC output of the tuned circuit is rectified by the diode CR4 and applied to a voltage divider consisting of resistors R1, R2, R3 and R4. The transistor Q1 compares the voltage in the wiper of the potentiometer R3 with the reference voltage set by the zener diode CR7. When the transistor Q1 is conducted, the transistor 42 functions as a switch to control the voltage of the coil in a relay contained in the encapsulated base. Both transistors Q1 and Q2 and the relay in the encapsulated base are activated when the frequency of the input voltage to terminals 1 and 2 is the normal frequency (50 to 60 hertz). When a sub frequency condition occurs, the voltage at the base of transistor Q1 is not sufficient for conduction. This causes the relay to be de-energized and its contacts to change. The low frequency trigger point is set by potentiometer R3.
The low-frequency relay (Figure 4-16) is a solid state device that works to protect the load on the frequency of the event generator that falls below the preset limits. It is activated when the frequency decreases to 55 hertz for 60 hertz operation and 46 hertz for 50 hertz operation. When actuated, the contacts within the relay are approached to signal the annunciator and are opened to deenergize the generator switch (contactor), resulting in a display of the fault condition and the elimination of the generator load.
Frequency detection is performed by a tuned circuit consisting of capacitors C1 and C2 and components in the encapsulated base. Zener diodes CR1, CR2 and CR3 limit the maximum voltage to the tuned circuit. The AC output of the tuned circuit is rectified by the diode CR4 and applied to a voltage divider consisting of resistors R1, R2, R3 and R4. The transistor Q1 compares the voltage in the wiper of the potentiometer R3 with the reference voltage set by the zener diode CR7. When the transistor Q1 is conducted, the transistor 42 functions as a switch to control the voltage of the coil in a relay contained in the encapsulated base. Both transistors Q1 and Q2 and the relay in the encapsulated base are activated when the frequency of the input voltage to terminals 1 and 2 is the normal frequency (50 to 60 hertz). When a sub frequency condition occurs, the voltage at the base of transistor Q1 is not sufficient for conduction. This causes the relay to be de-energized and its contacts to change. The low frequency trigger point is set by potentiometer R3.
|
« Next Oldest | Next Newest »
|
Important Note..!
If you are not satisfied with above reply ,..PleaseASK HERE
So that we will collect data for you and will made reply to the request....OR try below "QUICK REPLY" box to add a reply to this page| Tagged Pages: under frequency relay wikipedia, |
