Electrical contact materials used in switches, brushes and relays must possess 

 (A) high thermal conductivity and high melting point 

(B) Low thermal conductivity and low melting point 

 (C) High thermal conductivity and low melting point 

(D) Low thermal conductivity and high melting point.

1 Answer

Answer :

Electrical contact materials used in switches, brushes and relays must possess high thermal conductivity and high melting point 

Related questions

Last Answer : To protect most of the electrical equipment handling low power, the types of relays used are thermocouple, electronic and bimetallic.

Last Answer : Protective relays are devices that detect abnormal conditions in electrical circuits by measuring constantly the electrical quantities which differ during normal and abnormal conditions.

Description : When the master switch for the winch shown in the illustration is in the 'off' position, and the line & safe switches are closed, which of the listed relays should be energized? EL-0102 A. 'DB' & '2T' B. 'DB' & '4M' C. 'FR-B.O.' & 'LV' D. '1M' & '1A'

Last Answer : Answer: C

Description : On an engine throttle control system, the auxiliary control circuits are provided with devices to prevent excessive overtravel of the pilot valve by the synchronous motor. These devices are called _________________. A. overlap sensors B. limit switches C. overtravel relays D. proximity switches

Last Answer : Answer: B

Description : Motor controllers are seldom troubled with grounds because _____________. A. the auxiliary contacts have a high resistance connection B. the contactors and relays are mounted on a nonconducting panel ... individual series-connected units D. there are separate switches for the motor and the control

Last Answer : Answer: B

Description : Fault diverters are basically (a) fuses (b) relays (c) fast switches (d) circuit breakers

Last Answer : (c) fast switches

Description : As part of a routine maintenance program for deck machinery, you should ___________. A. inspect electrical wiring and pushbutton switches for evidence of corrosion or burned insulation B. disassemble ... covers and ventilate as weather permits D. Check drum switch contact pressure every three months

Last Answer : Answer: A

Description : Which of the following statements is true concerning the cleaning of electrical contacts? A. Compressed air should be used to blow out metallic dust. B. Magnetic brushes should be used to remove ... contact resistance. D. Delicate parts should be cleaned with a brush and an approved safety solvent.

Last Answer : Answer: D

Description : Define the following terms with respect to protective relays i) Relay time ii) Reset current iii) Plug setting multiplier and iv) Time setting multiplier

Last Answer : 1) Relay Time: The time interval between occurrence of fault and closure of relay contacts.  2) Reset Current: The value of current below which the relay resets and comes back to ... The adjustment arrangement provided for setting the operation time of relay is known as Time setting multiplier. 

Description :  For the protection of parallel feeders fed from one end, the relays used are: A) non-directional relays at the source-end and directional relays at the load-end B) non-directional relays at both the ... at the source-end and non-directional at the load-end D) directional relays at both the ends

Last Answer : For the protection of parallel feeders fed from one end, the relays used are: non-directional relays at the source-end and directional relays at the load-end

Description : Reactance relays are employed for Phase faults in : (A) Short lines (B) Medium lines (C) Long lines (D) Any line

Last Answer : Reactance relays are employed for Phase faults in : Short lines

Description : IDMT relays are used to protect the transformer against :  (A) Internal short -circuits (B) Open circuits (C) External short circuits (D) Oil leakage

Last Answer : IDMT relays are used to protect the transformer against : External short circuits

Last Answer : The inverse definite mean time relays are used for over current and earth fault protection of transformer against internal short-circuits.

Last Answer : The single phasing relays are used for the protection of three phase motors.

Last Answer : Impedance relays are used for phase faults on long line.

Last Answer : Discrimination between main and back up protection is provided by the use of relays which are slow.

Last Answer : Directional relays are based on flow of power.

Description : D.C. shunt relays are made of?

Last Answer : D.C. shunt relays are made of many turns of thin wire.

Last Answer : Thermal overload relays are used to protect the motor against overcurrent due to heavy loads.

Last Answer : Overload relays are of induction, solid state, thermal, electromagnetic type.

Last Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.

Last Answer : Oil switches are employed for high voltages and large currents circuits.

Last Answer : The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to extinguish the arc.

Description : To protect most of the electrical equipment handling low power, the types of relays used are (a) thermocouple (b) electronic and bimetallic (c) both (a) and (b) (d) none of the above

Last Answer : (c) both (a) and (b)

Description : Protective relays are devices that detect abnormal conditions in electrical circuits by measuring (a) current during abnormal condition (b) voltage during abnormal condition (c) constantly the electrical quantities which differ during normal and abnormal conditions (d) none of the above

Last Answer : (c) constantly the electrical quantities which differ during normal and abnormal conditions

Description : Which of the devices shown in the illustration automatically prevents the simultaneous operation of the windlass from both master switches? EL-0073 A. Selector switch B. Contact 'CR1a' C. Contact 'CR2a' D. Contact 'CR1D'

Last Answer : Answer: D

Description : Etched or burned bands on the contact faces of the brushes in a direct current generator can be caused by ____________. A. high mica segments B. copper drag on the commutator C. brushes improperly positioned D. copper embedded in the brushes

Last Answer : Answer: C

Description : The purpose of the commutator and brushes on a DC generator is to _____________. A. transfer generated direct current voltage from the armature to the line B. convert the alternating voltage ... contact method to excite the field D. reduce sparking between the armature and the carbon brushes

Last Answer : Answer: B

Last Answer : In D.C. generators, the brushes on commutator remain in contact with conductors which lie under interpolar region.

Description : What is the application and use of a range of electrical components Such as plugs switches sockets lighting and fittings junction boxes consumer units.?

Last Answer : Need answer

Description : When maintenance personnel are working on electrical equipment, all supply switches should be secured in the open position and tagged specifically by the _____________. A. watch engineer B. chief engineer or first assistant C. chief electrician D. person performing the repair

Last Answer : Answer: D

Description : Which of the following statements represents the FIRST precaution to be taken prior to working on any installed electrical component? A. Wear rubber gloves and boots. B. Use only approved nonconducting ... the machine before beginning any repairs. D. Open the supply circuits and tag the switches.

Last Answer : Answer: D

Description : Regarding the illustrated electrical schematic, 'S1-P', 'S1-Q', and 'S1-R' represent ____________. EL-0016 A. capacitors B. normally-closed contacts C. normally-open contacts D. normally-closed pushbutton switches

Last Answer : Answer: C

Description : Devices that transforms electrical signals into physical movements A. Sensors B. Actuators C. Switches D. Display

Last Answer : B. Actuators 

Description : What are the materials used to manufacture the brushes for slip rings of an induction motor?

Last Answer : A:The slip rings are made of brass and phosphor bronze. The brushes are made of metal graphite which is an alloy of copper and carbon.

Description : Sparking of D.C. motor brushes can be caused by __________. A. an open commutating winding B. many mechanical, electrical or operating faults C. an open interpole D. all of the above

Last Answer : Answer: B

Description : In actual applications, electrical connections to 'R1-R2' of figure 'A' and to 'R1-R2- R3' of figure 'B' shown in the illustration are made by ______________. EL-0092 A. soldered contacts B. spliced and taped connections C. slip rings and brushes D. solderless crimp-on connectors

Last Answer : Answer: C

Description : Which materials possess highest melting temperature? a.ABS b.PLA c.Nylon d.INF

Last Answer : c.Nylon

Description : Ceramic materials possess which of the following properties? a) Brittle and low dielectric constant b) Rigid and low dielectric constant c) Brittle and high dielectric constant d) Rigid and high dielectric constant

Last Answer : c) Brittle and high dielectric constant

Description : All types of plastids possess essentially the same structure because they (a) perform the same function (b) store food materials like starch, fat and protein (c) occur in aerial parts (d) can transform from one form to another

Last Answer : (d) can transform from one form to another.

Description : The plastics made from cellulose resin (A) Are as clear as glass (B) Are tough and strong (C) Possess excellent electrical properties (D) All the above

Last Answer : Answer: Option D

Description : Manganese steels (A) Are non-magnetic (B) Possess high electrical resistance (C) Possess low coefficient of expansion (D) All the above

Last Answer : Answer: Option D

Description : Brushes in a generator must be positioned in the neutral plane to avoid sparking between the brushes and the _____________. A. yoke B. armature windings C. field pole windings D. commutator

Last Answer : Answer: D

Last Answer : Overheating of relay contacts or contact born out is due to slow making and breaking of load circuit contacts, foreign matter on the contact surface, too low contact pressure.

Description : A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

Last Answer : A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

Description : What abilities must a cyber sleuth possess?

Last Answer : Dick

Description : A system exhibiting S.H.M. must possess – (1) Elasticity as well as inertia (2) Elasticity, inertia and an external force (3) Elasticity only (4) Inertia only

Last Answer : (1) Elasticity as well as inertia Explanation: Basic conditions to execute simple harmonic motion are: (i) There must be an elastic restoring force acting on the system, (ii) the system ... of the system should be directly proportional to its displacement and is always directed to mean position.

Description : A member of the BOA shall, at the time of his/her appointment, possess the following qualifications, except a. Must be a natural-born citizen and resident of the Philippines. b. Must not be a ... registered CPA with more than ten (10) years of work experience in any scope of practice of accountancy.

Last Answer : Must be a duly registered CPA with more than ten (10) years of work experience in any scope of practice of accountancy.