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Maritime Forum

Topics in Category: Marine electrotechnology

emo
Views: 158
Replies: 0
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PMA-3777's Avatar
Topic started 31 Oct 2016 16:06 by PMA-3777
When using portable electrical system or light so: A. What are the safety of personnel B. How to avoid compartment becomes dangerous
emo
Views: 96
Replies: 0
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PMA-3777's Avatar
Topic started 31 Oct 2016 16:01 by PMA-3777
Effect of prolong 3 phase induction motor while running when: A. Low voltage B. High frequency C. Blown of any one phase
emo
Views: 96
Replies: 0
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PMA-3777's Avatar
Topic started 31 Oct 2016 15:58 by PMA-3777
What charging is carried out in lead acid battery while charging or discharging: B. Reason for gassing C. What dangerous regards glassy and safety of compartment C. Why battery liquid is top up D. How to remove spillage on surface
emo
Views: 658
Replies: 3
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anandgardener's Avatar
Topic started 04 Feb 2012 19:43 by anandgardener
Give some of the applications of synchronous motors. How may the direction of rotation of a three phase motor be reversed? A 3-phase, 50 Hz, 6600 V, alternator is rated at 6600 kw at 0.8 power factor and a full-load efficiency of 90%. Determine KVA rating of the alternator, power input and horse...
class 1 exam candidate's Avatar
Last Post by class 1 exam candidate 09 Jun 2012 03:40
6600/0.8= 8250kVA 8250/.9=9167kW input = 12293shp
emo
Views: 224
Replies: 1
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anandgardener's Avatar
Topic started 04 Feb 2012 19:42 by anandgardener
A compound generator has a no-load voltage of 250 volts and a full-load voltage of 230 volts, and therefore, is considered to be _____________. (a) flat compounded (b) over compounded (c) under compounded (d) terminal compounded
jayant's Avatar
Last Post by jayant 31 May 2012 14:41
ans-a)flat compounded
emo
Views: 315
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:43 by anandgardener
Distinguish between power efficiency and all-day efficiency. Why is all-day efficiency considered more reasonable basis for comparison than ordinary efficiency. The no-load current of a transformer is 5.0 Amps, power factor 0.25 when supplied at 235 V, 50 Hz. Turns on the primary winding is 200....
emo
Views: 214
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:42 by anandgardener
An electrical device which employs a stationary armature and a rotating electromagnetic field is used a board ship as a ____________. (a) magnetic amplifier (b) ship's service alternator (c) three-wire DC generator (d) saturable core reactor
emo
Views: 188
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:42 by anandgardener
Differentiate between squirrel cage and wound rotor motors, of the three phase a.c. induction type, in respect of the following: (a) rotor construction; (b) torque characteristics; (c) speed variation
emo
Views: 185
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:41 by anandgardener
Describe an emergency electrical power generating plant for use in the event of a complete failure of the main electrical power and make reference to - (a) location (b) starting arrangements (c) fuel oil and its supply (d) cooling system (e) periodic attention required
emo
Views: 161
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:41 by anandgardener
With reference to electronic control systems: (a) Draw a simple block diagram for temperature control; (b) Describe each component shown in the diagram in (a).
emo
Views: 177
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:40 by anandgardener
A three-phase transformer has 560 turns on the primary and 42 turns on the secondry.The primary windings are connected to a line voltage of 6.6kV.Calculate the secondary line voltage when the transformer is connected (a) Star-Delta, (b) Delta-Star.
emo
Views: 215
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:39 by anandgardener
A battery is to consist of a number of cells connected in series. Each cell has an e.m.f. of 1.5V and an internal resistance of 0.5ohms. The external load has a resistance of 100ohms and requires approximately 2W for satisfactory operation. Determine how many cells will be required.
emo
Views: 159
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:39 by anandgardener
The magnetic field in the air gap of a two-pole motor has a flux density of 0.8T. The armature is wound with 246 conductors, each of 400mm effective length, mounted at 150mm effective radius, and at full load each conductor carries a current of 20A. Assuming that the actual torque produced is...
emo
Views: 152
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:38 by anandgardener
Differentiate conductors, semi-conductors and dielectrics. Explain their applications. What are the functional aspects of super conductors at room temperature?
emo
Views: 206
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:38 by anandgardener
The heating of conductors as a result of resistance in a distribution circuit causes a power loss expressed as_____________. (A) line droop (B) line loss (C) IR drop (D) hysteresis Justify your Answer with adequate reasoning and state why the other alternatives were ruled out.
emo
Views: 171
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:37 by anandgardener
Low horsepower, polyphase, induction motors can be started with full voltage by means of _____________. (A) compensator starters (B) autotransformer starters (C) across-the-line starters (D) primary-resistor starters Justify your Answer with adequate reasoning and state...
emo
Views: 157
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:37 by anandgardener
With reference to a three phase shipboard electrical distribution system: (a) Enumerate the advantages of an insulated neutral system; (b) Enumerate the disadvantages of an insulated neutral system; (c) Describe how the Earthed neutral system is Earthed; (d) Compare the use of an insulated neutral...
emo
Views: 196
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:36 by anandgardener
(a) State why front switch boards are required for A.C system having voltage to earth greater than 55V (b) Explain how section of an electrical system aboard ship can be isolated for maintenance work (c) Describe, with reference to electrical connections, the procedure to replace a 3-phase induction...
emo
Views: 186
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:36 by anandgardener
. (a) Describe a brush less alternator with a.c. exciter and static A.V.R. (b) State the output voltage characteristics for this type of machine.
emo
Views: 190
Replies: 0
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anandgardener's Avatar
Topic started 04 Feb 2012 19:35 by anandgardener
A bridge circuit containing zener diodes may be used in a static automatic voltage regulator to monitor the voltage output of an alternator. State: Details of operation of zener diodes. How the error signal is derived in the bridge circuit.
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