Answer / praveen kumar rai

In electronics, switches are classified according to the arrangement of their contacts. A pair of contacts is said to be "closed" when current can flow from one to the other. When the contacts are separated by an insulating air gap, they are said to be "open", and no current can flow between them at normal voltages. The terms "make" for closure of contacts and "break" for opening of contacts are also widely used.

The terms pole and throw are also used to describe switch contact variations. The number of "poles" is the number of separate circuits which are controlled by a single switch. For example, a "2-pole" switch has two separate identical sets of contacts controlled by the same switch. The number of "throws" is the number of separate wiring path choices other than "open" that the switch can adopt for each pole. A single-throw switch has one pair of contacts that can either be closed or open. A double-throw switch has a contact that can be connected to either of two other contacts, a triple-throw has a contact which can be connected to one of three other contacts, etc.[4]

In a switch where the contacts remain in one state unless actuated, such as a push-button switch, the contacts can either be normally open (abbreviated "n.o." or "no") until closed by operation of the switch, or normally closed ("n.c." or "nc") and opened by the switch action. A switch with both types of contact is called a changeover switch. These may be "make-before-break" ("MBB" or shorting) which momentarily connects both circuits, or may be "break-before-make" ("BBM" or non-shorting) which interrupts one circuit before closing the other.

These terms have given rise to abbreviations for the types of switch which are used in the electronics industry such as "single-pole, single-throw" (SPST) (the simplest type, "on or off") or "single-pole, double-throw" (SPDT), connecting either of two terminals to the common terminal.

what modulation is used in landline telephone signals?

2 Answers  

---

What is the pro & con of having 11kv & 33kv incoming, and what is the adv & disadv. of converting from 11kv to 33kv.

0 Answers  

---

What are Contactors? How they works and what its highest rating?

0 Answers  

---

electrical knowelge

0 Answers  

---

what will happen if a cw rotating altenator being synchronized to ccw rotating altenator

2 Answers  

---

why secondary of transformer always grouded?

1 Answers   IIUC, Sodexo,

---

ELECtrical

2 Answers   Bahwan Engineering, Bhel, Electrosteel, NBCC, Qatar Airlines,

---

which is best ac or dc

3 Answers  

---

What the difference between ac and dc inductor an capacitor

0 Answers  

---

how the length effects the ampacity of the cable? if a cable is carrying a current of 100A for 50m length then what will the effect on current if we double the length?

2 Answers  

---

what is the purpose of high speed earth switch in gas insulated substat

0 Answers   ABB,

---

What is difference between earth leakage relay and restricted earth fault relay ?

22 Answers  

---