Description : Cables for 220 kV lines are invariably (a) mica insulated (b) paper insulated (c) compressed oil or compressed gas insulated (d) rubber insulated (e) none of the above
Last Answer : (c) compressed oil or compressed gas insulated
Description : Capacitance grading of cable implies (a) use of dielectrics of different permeabilities (b) grading according to capacitance of cables per km length (c) cables using single dielectric in different ... introduced at different lengths to counter the effect of inductance (e) none of the above
Last Answer : (a) use of dielectrics of different permeabilities
Description : Copper as conductor for cables is used as (a) annealed (b) hardened and tempered (c) hard drawn (d) alloy with chromium
Last Answer : (a) annealed
Description : The electrostatic stress in underground cables is (a) same at the conductor and the sheath (b) minimum at the conductor and maximum at the sheath (c) maximum at the conductor and minimum at the sheath (d) zero at the conductor as well as on the sheath (e) none of the above
Last Answer : (c) maximum at the conductor and minimum at the sheath
Description : Solid type cables are considered unreliable beyond 66 kV because (a) insulation may melt due to higher temperature (b) skin effect dominates on the conductor (c) of corona loss between conductor and sheath material (d) there is a danger of breakdown of insulation due to the presence of voids
Last Answer : (d) there is a danger of breakdown of insulation due to the presence of voids
Description : The thickness of the layer of insulation on the conductor, in cables, depends upon (a) Reactive power (b) Power factor (c) Voltage (d) Current carrying capacity
Last Answer : (c) Voltage
Description : The thickness of metallic shielding on cables is usually (a) 0.04 mm (b) 0.2 to 0.4 mm (e) 3 to 5 mm (d) 40 to 60 mm
Last Answer : (a) 0.04 mm
Description : When measuring insulation resistance of cables using d.c. source, the galvanometer used should be initially short circuited because (A) Cables have a low value of capacitance which draws a high ... high value of charging current (D) Cables have a low value of capacitance and initial resistance
Last Answer : When measuring insulation resistance of cables using d.c. source, the galvanometer used should be initially short circuited because Cables have a high value of capacitance which draws a high value of charging current
Description : Why 1.1 kV grade cables used for 415V?
Last Answer : To take care of the both earthed / unearthed systems.
Description : What are the types of cables used in 6.6 kV and 415 V system voltages?
Last Answer : In 6.6 kV system AC (unearthed) grade having stranded aluminium conductors cables are used. Their insulation's are as follows. 1. XLPE - Crossed linked polyethylene insulation. 2. FRLS PVC - Fire ... V grade copper or aluminium stranded cables are used. Their insulations are HR PVC and FS type.
Description : Rubber is most commonly used insulation in cables. (a) Yes (b) No
Last Answer : (a) Yes
Description : In congested areas where excavation is expensive and inconvenient 'draw in system' of laying of underground cables is often adopted. (a) Yes (b) No
Description : It is difficult to maintain oil filled cables. (a) Yes (b) No
Description : The advantage of oil filled cables is (a) more perfect impregnation (b) smaller overall size (c) no ionisation, oxidation and formation of voids (d) all of the above
Last Answer : (d) all of the above
Description : The advantage of cables over overhead transmission lines is (a) easy maintenance (b) low cost (c) can be used in congested areas (d) can be used in high voltage circuits
Last Answer : (c) can be used in congested areas
Description : Underground cables are laid at sufficient depth (a) to minimise temperature stresses (b) to avoid being unearthed easily due to removal of soil (c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc. (d) for all of the above reasons
Last Answer : (c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc.
Description : The intersheaths in the cables are used to (a) minimize the stress (b) avoid the requirement of good insulation (c) provide proper stress distribution (d) none of the above
Last Answer : (c) provide proper stress distribution
Description : In the cables, sheaths are used to (a) prevent the moisture from entering the cable (b) provide enough strength (e) provide proper insulation (d) none of the above
Last Answer : (a) prevent the moisture from entering the cable
Description : In cables the charging current (a) lags the voltage by 90° (b) leads the voltage by 90° (c) lags the voltage by 180° (d) leads the voltage by 180°
Last Answer : (b) leads the voltage by 90°
Description : Cables, generally used beyond 66 kV are (a) oil filled (b) S.L. type (c) belted (d) armoured
Last Answer : (a) oil filled
Description : Pressure cables are generally not used beyond (a) 11 kV (b) 33 kV (c) 66 kV (d) 132 kV
Last Answer : (c) 66 kV
Description : In capacitance grading of cables we use a ______ dielectric. (a) composite (b) porous (c) homogeneous (d) hygroscopic
Last Answer : (a) composite
Description : High tension cables are generally used up to (a) 11kV (b) 33kV (c) 66 kV (d) 132 kV
Last Answer : (a) 11kV
Description : Low tension cables are generally used up to (a) 200 V (b) 500 V (c) 700 V (d) 1000 V
Last Answer : (d) 1000 V
Description : In single core cables armouring is not done to (a) avoid excessive sheath losses (b) make it flexible (c) either of the above (d) none of the above
Last Answer : (a) avoid excessive sheath losses
Description : Conduit pipes are normally used to protect _____ cables. (a) unsheathed cables (b) armoured (c) PVC sheathed cables (d) all of the above
Last Answer : (a) unsheathed cables
Description : cables are used for 132 kV lines. (a) High tension (b) Super tension (c) Extra high tension (d) Extra super voltage
Last Answer : (d) Extra super voltage
Description : The current carrying capacity of cables in D.C. is more that in A.C. mainly due to (a) absence of harmonics (b) non-existence of any stability limit (c) smaller dielectric loss (d) absence of ripples (e) none of the above
Last Answer : (c) smaller dielectric loss
Description : The insulating material for cables should (a) be acid proof (b) be non-inflammable (c) be non-hygroscopic (d) have all above properties
Last Answer : (d) have all above properties
Description : Which of the following insulation is used in cables? (a) Varnished cambric (b) Rubber (c) Paper (d) Any of the above
Last Answer : (d) Any of the above
Description : What are power cables? Explain about them?
Last Answer : TYPES AND APPLICATIONS Presently PVC and XLPE cables are being used in electrical installations. The discussion is restricted to these two types only. The voltage ratings covered are up to and including ... short time overload up to 120°C and, In systems having higher short circuit levels.
Description : How to Hide Speaker Cables
Last Answer : How to Hide Speaker Cables Setting up your new home theater should be planned properly since you don't want speaker cables cluttering up all the space. With careful planning, you should be able to place ... cables. You can simply just install a low cost cable run to hook up any new devices.
Description : Draw and explain the construction of underground cables.
Last Answer : Underground cables: OR Explanation:- i) Core or conductor: * It function is carry current. * Cable may have single or more than single core conductor. * Conductor ... handling of cables. * It is similar to bedding & consists of fiborous material such as jute.
Description : the classification of cables. (i) According with voltage levels. (ii) According to numbers of core.
Last Answer : 1. Classification of cables with their voltage levels: 1. Low voltage (tension) cable/LT cable: for operating voltage 1.1 KV. 2. High voltage (tension) cable/HT cable: for operating voltage 11 KV. 3. Super ... 4. Three & half core cable. 5. Four core cable 6. Six core cable 7. Multi core cable
Description : How the required conductor size can be reduced by use of HRC fuses?
Last Answer : HRC fuse limits the peak amplitude of fault current. HRC fuse melts at prospective current but not allows circuit to pass their high rupturing capacity that is it’s kA.
Description : In a cable the voltage stress is maximum at (a) sheath (6) insulator (e) surface of the conductor (d) core of the conductor
Last Answer : (d) core of the conductor
Description : PVC stands for (a) polyvinyl chloride (b) post varnish conductor (c) pressed and varnished cloth (d) positive voltage conductor (e) none of the above
Last Answer : (a) polyvinyl chloride
Description : In a cable, the maximum stress under operating conditions is at (a) insulation layer (b) sheath (c) armour (d) conductor surface
Last Answer : (d) conductor surface
Description : The minimum dielectric stress in a cable is at (a) armour (b) bedding (c) conductor surface (d) lead sheath
Last Answer : (d) lead sheath
Description : The material for armouring on cable is usually (a) steel tape (b) galvanised steel wire (c) any of the above (d) none of the above
Last Answer : (c) any of the above
Description : The surge resistance of cable is (a) 5 ohms (b) 20 ohms (c) 50 ohms (d) 100 ohms
Last Answer : (c) 50 ohms
Description : ACSR (Aluminium Conductor Steel Reinforced) are used as (A) over head transmission lines. (B) super conductors. (C) fuse (D) underground cables.
Last Answer : (A) over head transmission lines.
Description : What is the type cable used in radiation areas?
Last Answer : Mineral insulated (MI) cables.
Description : Why bimetallic washers provided in aluminium copper transition joints?
Last Answer : To avoid galvanic corrosion failure.
Description : Why armouring done?
Last Answer : For mechanical strength, protect against damage by impact of an object.
Description : How armours /sheaths grounded?
Last Answer : 1 core cables -- sheaths/shields/armours grounded at one end only, other end insulated to prevent the circulating current through sheaths. 3 core cables -- grounded at both ends but not including core balance CT’s, since even small induced current causes 50N operation.
Description : What is the specified cable life?
Last Answer : 50 years.
Description : What are the advantages of XLPE?
Last Answer : a. Easy routing at heights b. Easy maintenance c. Large current (90 ºC) d. No sheath (no fatigue) e. No paper tape wrapping technique f. High dielectric strength g. Very little deformation ... i. Low tan delta and hence suits long routes j. Very light k. Good mechanical properties.
Description : What are the disadvantages of paper insulation?
Last Answer : a. Absorbs moisture. b. Cable termination/sealing problems.
Description : What are the purposes of cable trays?
Last Answer : a. Avoid sagging of cables b. Give mechanical support