Why alternator not building up voltage
Loss of residual magnetism cos it was idle for long time or it was motored before;
Field excitation ckt is open or very high resistance
wire broken
voltmeter faulty,
too many rotary diode shorted or fuse of diode blown
rectifier,transformer…..
ALTERNATOR HEATING
Is due to friction and windage loss, core loss, tooth loss, stator and rotor copper loss, stray loss
Friction and windage loss is due to the overhang portion of the windings which cause heat generation due to air friction.
Core loss is due to hysteresis loss and eddy current loss
Tooth loss is due to cross armature reaction depending on the load
Copper loss are due to its internal resistance
Stray losses is caused by alternating stray fluxes that appear, in loaded condition, in the pole faces, teeth,core,over hang.
Due to heating on load, voltage drop increases inside the alternator and terminal voltage drops. This voltage drop is due to winding resistance, leakage reactance and armature reaction. Due to the reduced terminal voltage, the load equipment is compelled to draw more current to derive same power.
To reduce – well ventilated, duct pointing to the alternator, air filter mesh for circulating air, end brgs are lubricated sufficiently to avoid heat generation due to friction
What is AMP
It is ALTENATE MARITIME POWER. Shore supply. Port of L.A was first to adopt it and is done basically for clean air to the port
Interpoles and its function
Small poles fixed to the yoke in btw the main poles. They are wound with few heavy Copper wire turns and are connected in series with the main winding.
Neutralizes the cross-magnetising effect of the armature reaction
Makes commutation sparkless
SARKAR ALTERNATOR
Advantages of brushless over conventional alternator?
No brushes hence no downtime maintainence and also no sparks.
It makes use of field boosting so that recovery time of any voltage dip is recovered in abt 0.6sec compared to 1.8sec taken by conventional alternators using carbon pile AVR
Brushless alternator and advantages?
A brushless alternator is composed of two alternators built end-to-end on one shaft. The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils). The main alternator uses the opposite configuration with a rotating field and stationary armature.
Exciter
The exciter field coils are on the stator and its armature is on the rotor. The AC output from the exciter armature is fed through a set of diodes that are also mounted on the rotor to produce a DC voltage. This is fed directly to the field coils of the main alternator, which are also located on the rotor. With this arrangement, brushes and slip rings are not required to feed current to the rotating field coils. This can be contrasted with a simple automotive alternator where brushes and slip rings are used to supply current to the rotating field.
Main Alternator
The main alternator has a rotating field as described above and a stationary armature (power generation windings).
Loss of residual magnetism cos it was idle for long time or it was motored before;
Field excitation ckt is open or very high resistance
wire broken
voltmeter faulty,
too many rotary diode shorted or fuse of diode blown
rectifier,transformer…..
ALTERNATOR HEATING
Is due to friction and windage loss, core loss, tooth loss, stator and rotor copper loss, stray loss
Friction and windage loss is due to the overhang portion of the windings which cause heat generation due to air friction.
Core loss is due to hysteresis loss and eddy current loss
Tooth loss is due to cross armature reaction depending on the load
Copper loss are due to its internal resistance
Stray losses is caused by alternating stray fluxes that appear, in loaded condition, in the pole faces, teeth,core,over hang.
Due to heating on load, voltage drop increases inside the alternator and terminal voltage drops. This voltage drop is due to winding resistance, leakage reactance and armature reaction. Due to the reduced terminal voltage, the load equipment is compelled to draw more current to derive same power.
To reduce – well ventilated, duct pointing to the alternator, air filter mesh for circulating air, end brgs are lubricated sufficiently to avoid heat generation due to friction
What is AMP
It is ALTENATE MARITIME POWER. Shore supply. Port of L.A was first to adopt it and is done basically for clean air to the port
Interpoles and its function
Small poles fixed to the yoke in btw the main poles. They are wound with few heavy Copper wire turns and are connected in series with the main winding.
Neutralizes the cross-magnetising effect of the armature reaction
Makes commutation sparkless
SARKAR ALTERNATOR
Advantages of brushless over conventional alternator?
No brushes hence no downtime maintainence and also no sparks.
It makes use of field boosting so that recovery time of any voltage dip is recovered in abt 0.6sec compared to 1.8sec taken by conventional alternators using carbon pile AVR
Brushless alternator and advantages?
A brushless alternator is composed of two alternators built end-to-end on one shaft. The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils). The main alternator uses the opposite configuration with a rotating field and stationary armature.
Exciter
The exciter field coils are on the stator and its armature is on the rotor. The AC output from the exciter armature is fed through a set of diodes that are also mounted on the rotor to produce a DC voltage. This is fed directly to the field coils of the main alternator, which are also located on the rotor. With this arrangement, brushes and slip rings are not required to feed current to the rotating field coils. This can be contrasted with a simple automotive alternator where brushes and slip rings are used to supply current to the rotating field.
Main Alternator
The main alternator has a rotating field as described above and a stationary armature (power generation windings).
Avr with full diagram?
Draw and explain voltage dip and transitional time period ?
Types of excitation system. Which one you have in last ship – 65DT hall
Rotary exciters and static exciters
What is motoring? (Reverse power)
Safeties in alternator?
Instantaneous overload relay – 2-10times the rated FLC with 0.1-3sec
Sustained overcurrent of IDMT type with preferential trip- 110% of rated FLC; 0.7-2times FLC with 1-10sec
Reverse power trip for alt (turbine- 2-3% & diesel 5-15% with a time delay of 0.5-3sec)and rev current trip for DC Generator
Under voltage protection delay with time delay(80% of rated voltage)
Over voltage (120% of rated voltage)
Under Freq(58) and Over Freq (62)
Differential protection for short circuit inside the alternator at 0.1 times the rated current
Negative Phase sequence relay determines the amount of unbalance in the stator currents which is a measure of rotor and stator temp. 0.2 times rated current
HRC fuse for short circuit prot
Earth leakage relay or sometimes called zero phase sequence detects earth fault current returning back to earthed neutral connection.
Master lock out is a protection relay which trips the prime mover and also suppresses the generator field
Draw and explain voltage dip and transitional time period ?
Types of excitation system. Which one you have in last ship – 65DT hall
Rotary exciters and static exciters
What is motoring? (Reverse power)
Safeties in alternator?
Instantaneous overload relay – 2-10times the rated FLC with 0.1-3sec
Sustained overcurrent of IDMT type with preferential trip- 110% of rated FLC; 0.7-2times FLC with 1-10sec
Reverse power trip for alt (turbine- 2-3% & diesel 5-15% with a time delay of 0.5-3sec)and rev current trip for DC Generator
Under voltage protection delay with time delay(80% of rated voltage)
Over voltage (120% of rated voltage)
Under Freq(58) and Over Freq (62)
Differential protection for short circuit inside the alternator at 0.1 times the rated current
Negative Phase sequence relay determines the amount of unbalance in the stator currents which is a measure of rotor and stator temp. 0.2 times rated current
HRC fuse for short circuit prot
Earth leakage relay or sometimes called zero phase sequence detects earth fault current returning back to earthed neutral connection.
Master lock out is a protection relay which trips the prime mover and also suppresses the generator field
ALTERNATOR MAINTENANCE
All wirings for damage and terminal conn tightness
Cleaning and drying of air filter and ventilation passages are free of dust
Blowing out dirt on windings using a vacuum cleaner or dry lint-free cloth
Removing if any oil deposits on windings
Minor windind damage repaired by dry varnish
Checking the air gap (usu 2-3mm in the middle)
Insulation resistance of windings( min 1Mohm usu 1Kohm/1volt is the rule) and remember to isolate nay electronic components which can get damaged---- check polarization index test if insulation reduced after using heating….. ratio of insulation res after cranking for 10min to IR value of cranking for one min…..
If it is increasing more than 1, then heating is effective…. Otherwise, sth is broken and rewinding is reqd)
All wirings for damage and terminal conn tightness
Cleaning and drying of air filter and ventilation passages are free of dust
Blowing out dirt on windings using a vacuum cleaner or dry lint-free cloth
Removing if any oil deposits on windings
Minor windind damage repaired by dry varnish
Checking the air gap (usu 2-3mm in the middle)
Insulation resistance of windings( min 1Mohm usu 1Kohm/1volt is the rule) and remember to isolate nay electronic components which can get damaged---- check polarization index test if insulation reduced after using heating….. ratio of insulation res after cranking for 10min to IR value of cranking for one min…..
If it is increasing more than 1, then heating is effective…. Otherwise, sth is broken and rewinding is reqd)
In brushless alternator, rotating diode and fuses checked for continuity; transformer, avr, zener…. Free of dust and oil and dampness
In conventional alternator, slip rings checked for uniform wear and brushes for movement. Brushes spring press checked pull type spring balance of 1-1.4kg.
The brushes length is also important as shorter(below 2cm) brushes create spark. New ones of correct size to be chosen and have to check if it is of same shape as the slip ring.
MSB protection
Sectioning thru bus tie bar
Dead front panel - live wire behind and covered with insulating plates
Hinged doors are earthed and cannot be opened unless the breaker is put off
Fused isolators are isolating switches which incorporate fuses
CB are of draw out type and can be easily drawn only if they r properly isolated
Drip proof protection
No pipelines above
Sufficient space around of atleast 0.6m
Ebonite rods
Insulating mat of atleast 3mm front and back
MSB on raised platform
In conventional alternator, slip rings checked for uniform wear and brushes for movement. Brushes spring press checked pull type spring balance of 1-1.4kg.
The brushes length is also important as shorter(below 2cm) brushes create spark. New ones of correct size to be chosen and have to check if it is of same shape as the slip ring.
MSB protection
Sectioning thru bus tie bar
Dead front panel - live wire behind and covered with insulating plates
Hinged doors are earthed and cannot be opened unless the breaker is put off
Fused isolators are isolating switches which incorporate fuses
CB are of draw out type and can be easily drawn only if they r properly isolated
Drip proof protection
No pipelines above
Sufficient space around of atleast 0.6m
Ebonite rods
Insulating mat of atleast 3mm front and back
MSB on raised platform
MSB SAFETIES AND TESTING
Fuse isolators
CB with Overcurrent tested by current injection method- primary injection and secondary injection
Under voltage – will close the stdby generator breaker
Reverse power- reducing the load gradually down….
MSB Maintenance (unknown)
Fuse isolators
CB with Overcurrent tested by current injection method- primary injection and secondary injection
Under voltage – will close the stdby generator breaker
Reverse power- reducing the load gradually down….
MSB Maintenance (unknown)
Nut bolt Conn and checks shud be checked for tightness
Vacuum cleaner for dust
Remove if any dead lizards
Check insulators on which bar r held are in place and not damaged
Check for signs of overheating
Vacuum cleaner for dust
Remove if any dead lizards
Check insulators on which bar r held are in place and not damaged
Check for signs of overheating
Incoming cables for soundness and glands
Aux winding for soundness
Earth bonding of panel doors to b checked
Operation of bus tie to be checked
Switches and indication lamps checked
Safety devices
Why reverse current and over current trip provided?
Reverse current is provided for DC generator for protecting mc from motoring
Current injection? (over current test)
If ship p.f is less, how it will affect marpol and ship owner
Disadv of low P.F
Cost of generating station and distribution eq is more for a given load
Makes voltage regualtions poor
For transmission of same power, low pf means more conductor and hence more energy for the same size of conductor
For the same KW load, lower power factor requires more magnetizing current which means more current passing and requires large cable size – means more capital cost and more cu loss and more
As the reactivecomponent is more, wasting energy in not doing useful work
Aux winding for soundness
Earth bonding of panel doors to b checked
Operation of bus tie to be checked
Switches and indication lamps checked
Safety devices
Why reverse current and over current trip provided?
Reverse current is provided for DC generator for protecting mc from motoring
Current injection? (over current test)
If ship p.f is less, how it will affect marpol and ship owner
Disadv of low P.F
Cost of generating station and distribution eq is more for a given load
Makes voltage regualtions poor
For transmission of same power, low pf means more conductor and hence more energy for the same size of conductor
For the same KW load, lower power factor requires more magnetizing current which means more current passing and requires large cable size – means more capital cost and more cu loss and more
As the reactivecomponent is more, wasting energy in not doing useful work
Causes of low power factor
Transformer run at low load drawing more magnetizing current
Large use of IM at low loads
Arc lamps
Transformer run at low load drawing more magnetizing current
Large use of IM at low loads
Arc lamps
How to increase PF on ship. Basics of power factor - 57 of mitra
Is defined as the cosine of the phase angle btw V and current in ac circuits
In an ac circuit, V & I are vector quantites having magnitude and direction at any instant.
In a resistive circuit, V & I are in phase, so The active power consumption is Vrms * Irms.
In an purely inductor, the electrical energy is stored in the form of magnetic energy. The current lags voltage by 90.
In a purely capacitor, electrical energy in the form of electrostatic energy. The current lags voltage by 90.
In a combination circuit, p.f. will be lagging if XL>XC and pf is leading is XC>XL
Power factor= true power/apparent power=(VIcos@) / VI [kW/kVA]
Is defined as the cosine of the phase angle btw V and current in ac circuits
In an ac circuit, V & I are vector quantites having magnitude and direction at any instant.
In a resistive circuit, V & I are in phase, so The active power consumption is Vrms * Irms.
In an purely inductor, the electrical energy is stored in the form of magnetic energy. The current lags voltage by 90.
In a purely capacitor, electrical energy in the form of electrostatic energy. The current lags voltage by 90.
In a combination circuit, p.f. will be lagging if XL>XC and pf is leading is XC>XL
Power factor= true power/apparent power=(VIcos@) / VI [kW/kVA]
It is the percentage of power available to do useful work.
METHODS OF IMPROVING POWER FACTOR
Not Running IM in low loads and using high speed IM
Static Capacitor providing leading current when capacitor bank is connected in parallel to load
Synchronous condenser is nothing but synchronous motor with over excitation and no load current. It gives leading current and works like a capacitor. When synchronous condenser is connected across the supply voltage in parallel, then it provides reactive component reqd for the inductive load.
Phase Advancer is a particular type of AC exciter which is connected to the rotor circuit of an IM. It is connected on the shaft of the motor. By providing more ampere-turns than reqd, IM can be made to operate on leading PF like an over excited SM. Current is injected thru the slip rings of the motor, which is leading with regard to the rotor voltage. This current relieves the stator current from providing the magnetizing current, thus improving pf.
Types of earthing?
EARTHED NEUTRAL SYSTEM
Is used where any single fault current is passes thru the hull and has potential to pass thru the hull into another equipment and damage
We can get 2 system voltages
Easier to locate the earth fault by earth fault relay placed in neutral earth line,
In the event of inductive or capacitive faults, the voltage surge can rise to 3.5-4 times the system voltage to earth. Since it is only VL/3, it is small compared to neutral earthed system
In ships with more than one generator neutral earthed, circulating harmonic current will be there and cause stator loss and extra heating.
Thus for 3.3kv, a NER is provided to limit the the earth fault current. This reduces the fire risk and over voltage problem.
INSULATED NEUTRAL SYSTEM
Used wher it is required for an uninterrupted supply to essential services for navigation and propulsion
One single earth fault doesn’t interrupt the supply but gives an alarm
In the event of inductive or capacitive faults, the voltage surge can rise to 3.5-4 times the system voltage which is VL.
Low values of the earth fault current reduces the risk of fire
Earth fault is difficult to find as the earth fault is indicated in which only phase fault is found and then done in trial and error method
Sometimes, the alternator has its third harmonic currents and have no return path for them to flow btw generator windings, in neutral earthed system.
Emergency power supply?
Emergency generator solas?
Not Running IM in low loads and using high speed IM
Static Capacitor providing leading current when capacitor bank is connected in parallel to load
Synchronous condenser is nothing but synchronous motor with over excitation and no load current. It gives leading current and works like a capacitor. When synchronous condenser is connected across the supply voltage in parallel, then it provides reactive component reqd for the inductive load.
Phase Advancer is a particular type of AC exciter which is connected to the rotor circuit of an IM. It is connected on the shaft of the motor. By providing more ampere-turns than reqd, IM can be made to operate on leading PF like an over excited SM. Current is injected thru the slip rings of the motor, which is leading with regard to the rotor voltage. This current relieves the stator current from providing the magnetizing current, thus improving pf.
Types of earthing?
EARTHED NEUTRAL SYSTEM
Is used where any single fault current is passes thru the hull and has potential to pass thru the hull into another equipment and damage
We can get 2 system voltages
Easier to locate the earth fault by earth fault relay placed in neutral earth line,
In the event of inductive or capacitive faults, the voltage surge can rise to 3.5-4 times the system voltage to earth. Since it is only VL/3, it is small compared to neutral earthed system
In ships with more than one generator neutral earthed, circulating harmonic current will be there and cause stator loss and extra heating.
Thus for 3.3kv, a NER is provided to limit the the earth fault current. This reduces the fire risk and over voltage problem.
INSULATED NEUTRAL SYSTEM
Used wher it is required for an uninterrupted supply to essential services for navigation and propulsion
One single earth fault doesn’t interrupt the supply but gives an alarm
In the event of inductive or capacitive faults, the voltage surge can rise to 3.5-4 times the system voltage which is VL.
Low values of the earth fault current reduces the risk of fire
Earth fault is difficult to find as the earth fault is indicated in which only phase fault is found and then done in trial and error method
Sometimes, the alternator has its third harmonic currents and have no return path for them to flow btw generator windings, in neutral earthed system.
Emergency power supply?
Emergency generator solas?
MITRA ALTLERNATOR
Generators not sharing KW load? You took AE on load after some time you saw one taking more load, why? Droop and how to adjust
Droop of governor is not set properly. For two generators to run in parallel, it must have same droop characteristics within a tolerance of =/- 0.5%
A governor with 2% droop means a 2% variation of speed will raise the load from 0to 100.
Too low droop- high sensitivity and instability
Too high droop – gov late response
Droop is set by compensation arrangement in which needle has to be adjusted manually by trial and error method and then has to be locked.
2 alternators are running in parallel and supplying unequal currents. What should be the reason for this? how would their power factors and kvar load shared be related
If droop of the AVR is not same, then the KVAR loading will be different and unequal current distribution. There is a voltage trimmer inside the MSB, by varying the potentiometer, we change the resistance and thus change the KVAR sharing.
Two AE in parallel showing same voltage but different current and power factor, why?
KW loading is based on the droop of governor.
KVAR load sharing is dependent on droop of the AVR.
How to improve PF other than capacitor
Alternator stator – star or delta. Y delta not used
For the same no of turns, star generates more voltage
For the same line voltage gen, amount of insulation reqd is also less
Star provides a neutral which can be earthed or insilated and also helps in gving another sys voltage thru neutral
By using star connection, we have Vph= 1/3 of VL
That means the conductors used per phase is less
What is the value of AVR voltage and current in alternator
110V and 80 amps
Value of air gap in alternator and significance of it?
2-3mm.
If more, the reluctance of the air gap increases which reduces the flux density passing and hence less alternating flux will cut and less emf is induced.
If less, voltage will be more due to increased flux density but we will have a non uniform voltage waveform and overheating problems
Generators not sharing KW load? You took AE on load after some time you saw one taking more load, why? Droop and how to adjust
Droop of governor is not set properly. For two generators to run in parallel, it must have same droop characteristics within a tolerance of =/- 0.5%
A governor with 2% droop means a 2% variation of speed will raise the load from 0to 100.
Too low droop- high sensitivity and instability
Too high droop – gov late response
Droop is set by compensation arrangement in which needle has to be adjusted manually by trial and error method and then has to be locked.
2 alternators are running in parallel and supplying unequal currents. What should be the reason for this? how would their power factors and kvar load shared be related
If droop of the AVR is not same, then the KVAR loading will be different and unequal current distribution. There is a voltage trimmer inside the MSB, by varying the potentiometer, we change the resistance and thus change the KVAR sharing.
Two AE in parallel showing same voltage but different current and power factor, why?
KW loading is based on the droop of governor.
KVAR load sharing is dependent on droop of the AVR.
How to improve PF other than capacitor
Alternator stator – star or delta. Y delta not used
For the same no of turns, star generates more voltage
For the same line voltage gen, amount of insulation reqd is also less
Star provides a neutral which can be earthed or insilated and also helps in gving another sys voltage thru neutral
By using star connection, we have Vph= 1/3 of VL
That means the conductors used per phase is less
What is the value of AVR voltage and current in alternator
110V and 80 amps
Value of air gap in alternator and significance of it?
2-3mm.
If more, the reluctance of the air gap increases which reduces the flux density passing and hence less alternating flux will cut and less emf is induced.
If less, voltage will be more due to increased flux density but we will have a non uniform voltage waveform and overheating problems
Ship operates on 60Hz, what will happen if operates on 50Hz?
Speed of the motors is prop to freq
And delivered output and head is prop to speed
Power consumption is also prop to cube of speed
Since freq reduced by 16.7%, moor stator winding current will be higher by abt 16.7% as their impedance is dependant on the freq.
The higher current if unnoticed, can cause damage to insulation in the long run and burn out
SOLUTION- I is prop to V/Z i.e. V/f………… hence by maintain v/f ratio same, the prob can be solved. So the voltage has to be dropped by same 16.7%. this can be changed by changing the tap end transformer
What checks made on an alternator after it is been tripped on over speed.
Mechanical checks – rotating components…. Any two units opened up for inspection of cracks, deformations. Ring grooves, rings, gudgeon pin and its bushes, con rod trueness and length, crank pin and bearing, c/shaft deflection. Any two main bearings opened and checked.crankcase, gear case,camshaft,cams,rollers. Crankcase l.o also checked as it might got overheated and oxidised All con rod bolts changed compulsorily.
Electrical – diodes, avr excitation windings, check if conductors got displaced, main alternator windings for damage, insulation testing, air gap,
What is D in the ME electronic governor? IPAD
Motor on top of governor, how it is rotating
Is called synchronizing motor or speed setting motor and runs only on DC.
Purpose is to provide a means of remote speed adjustments. It enables the remote switchboard operator to match the freq of the alternator with that of the other alternator…… so that load is distributed evenly when running parallel in droop.
PID controller, how integral and derivative actions are achieved in electronic governor on AE
in HV system, what protection alternator provided.
VCB or SF6 CB
High impedance NER to limit earthing current
Speed of the motors is prop to freq
And delivered output and head is prop to speed
Power consumption is also prop to cube of speed
Since freq reduced by 16.7%, moor stator winding current will be higher by abt 16.7% as their impedance is dependant on the freq.
The higher current if unnoticed, can cause damage to insulation in the long run and burn out
SOLUTION- I is prop to V/Z i.e. V/f………… hence by maintain v/f ratio same, the prob can be solved. So the voltage has to be dropped by same 16.7%. this can be changed by changing the tap end transformer
What checks made on an alternator after it is been tripped on over speed.
Mechanical checks – rotating components…. Any two units opened up for inspection of cracks, deformations. Ring grooves, rings, gudgeon pin and its bushes, con rod trueness and length, crank pin and bearing, c/shaft deflection. Any two main bearings opened and checked.crankcase, gear case,camshaft,cams,rollers. Crankcase l.o also checked as it might got overheated and oxidised All con rod bolts changed compulsorily.
Electrical – diodes, avr excitation windings, check if conductors got displaced, main alternator windings for damage, insulation testing, air gap,
What is D in the ME electronic governor? IPAD
Motor on top of governor, how it is rotating
Is called synchronizing motor or speed setting motor and runs only on DC.
Purpose is to provide a means of remote speed adjustments. It enables the remote switchboard operator to match the freq of the alternator with that of the other alternator…… so that load is distributed evenly when running parallel in droop.
PID controller, how integral and derivative actions are achieved in electronic governor on AE
in HV system, what protection alternator provided.
VCB or SF6 CB
High impedance NER to limit earthing current
Overcurrent trip, how is it tested, where to inject current?
Reverse power trip how to try out, what will happen if trip not activated?
Diff between earthing and bonding?
Variable voltage variable frequency controller
Reverse power trip how to try out, what will happen if trip not activated?
Diff between earthing and bonding?
Variable voltage variable frequency controller
BHOUMIK alternator
Why pf is lagging and not leading?301
Significance of PF? 301
Why do we prefer AC than DC?
No maintenance- no slip rings and brushes
Power transmission is easy by using transf
Plant cost for AC transmission is much lower than equivalent DC transmission
When a large fault current occurs, it is easy to interrupt ac as sine wave tend to become zero at some point.
AE governor droop significance
Emergency generator and its working? Interlocks and time etc
Synchroscope operation and detail? Written notes
Tolerance - -10to+10% of phase angle and freq slip of +/-0.067Hz if synchro rotating at 4rpm.
Different types of single phase protection? Negative phase relay
Reverse power trip arrangement and purpose?
How generator connected to bus bar exactly?
Single phasing and short circuit prevention equipment? Pg62
How to order new DG without having any information from old DG(name plate marking gone) he was asking for some manual which we have on ship to find how much capacity is required
Checks to be made before opening backside of MSB?
Fluctuation on load while two generators are running in parallel. Reason
Earthing system in tankers and advantages? 295
Why pf is lagging and not leading?301
Significance of PF? 301
Why do we prefer AC than DC?
No maintenance- no slip rings and brushes
Power transmission is easy by using transf
Plant cost for AC transmission is much lower than equivalent DC transmission
When a large fault current occurs, it is easy to interrupt ac as sine wave tend to become zero at some point.
AE governor droop significance
Emergency generator and its working? Interlocks and time etc
Synchroscope operation and detail? Written notes
Tolerance - -10to+10% of phase angle and freq slip of +/-0.067Hz if synchro rotating at 4rpm.
Different types of single phase protection? Negative phase relay
Reverse power trip arrangement and purpose?
How generator connected to bus bar exactly?
Single phasing and short circuit prevention equipment? Pg62
How to order new DG without having any information from old DG(name plate marking gone) he was asking for some manual which we have on ship to find how much capacity is required
Checks to be made before opening backside of MSB?
Fluctuation on load while two generators are running in parallel. Reason
Earthing system in tankers and advantages? 295
BHATTA ALTERNATOR
Reverse power trip principle and diagram. Reverse power trip and method of testing? 209
Reverse power trip principle and diagram. Reverse power trip and method of testing? 209
189
Function of bus bar. How bus bar fitted and why in that way? 185
Function of bus bar. How bus bar fitted and why in that way? 185
Shore connection box? Specification
Sys volt, sys amp, terminal size, earthing cable.
Alternator maintenance? 117
Two alternators has arrived onboard, same rating. One for DG and other for steam turbine. Just by looking how will you decide which one for what? 118
Maintenance of running alternator? 117
Why air gap in alternator?119
Stator winding connection how and why. Advantage? 120
Advantage of each test of alternator
Salient pole alternator used in? 101
What is residual magnetism, significance in generator, how to restore?
How fault find in insulated system.
Insulated neutral system advantage?
Diff between bonding and earthing?
Insulation and resistance difference?
Diff btw distribution board, section board, feeder board and MSB? I books
Difference between MSB and section boards. safeties in section board
ACB safeties. Short circuit trip test (over current trip)?
Diff between earthing and bonding?
Variable voltage variable frequency control
Sys volt, sys amp, terminal size, earthing cable.
Alternator maintenance? 117
Two alternators has arrived onboard, same rating. One for DG and other for steam turbine. Just by looking how will you decide which one for what? 118
Maintenance of running alternator? 117
Why air gap in alternator?119
Stator winding connection how and why. Advantage? 120
Advantage of each test of alternator
Salient pole alternator used in? 101
What is residual magnetism, significance in generator, how to restore?
How fault find in insulated system.
Insulated neutral system advantage?
Diff between bonding and earthing?
Insulation and resistance difference?
Diff btw distribution board, section board, feeder board and MSB? I books
Difference between MSB and section boards. safeties in section board
ACB safeties. Short circuit trip test (over current trip)?
Diff between earthing and bonding?
Variable voltage variable frequency control
BHATTA ALTERNATORS
Shaft generator advantage? 268
HV system advantage and range. Safety?
Advantage
High voltage means less current- means the size of the conductor can be reduced
Less current means less copper losses, hence transmission losses are less
Less current also measn less voltage drop, hence better voltage regulation
Shaft generator advantage? 268
HV system advantage and range. Safety?
Advantage
High voltage means less current- means the size of the conductor can be reduced
Less current means less copper losses, hence transmission losses are less
Less current also measn less voltage drop, hence better voltage regulation
Why we earth in HV system? Prot in steering motor for single earth fault
Supplied via transformers, whose sec winding is not earthed.
Supplied via transformers, whose sec winding is not earthed.
Harmonic filter?
Skin effect and proximity effect?
Skin effect and proximity effect?
The toroidal winding machines has controlled by microcontroller in light of the way that it has ease program and control. This structure has secured for maker, heads and its speed can be controlled, which is creature key for minor windings. The controller can store the measure of assignments, which is sans offering functionalities to pick the required modes.toroidal winding machine
ReplyDeleteAnother material is kool mu is sensible cost and it has show the lower loads and in a general sense goliath warm properties when related with controlled iron fixation interests. The kool mu is key utilize when the high flux thickness and low obsession stacks fittingly figure change circuits same as unidirectional drive application like heartbeat transformer and flyback transformer. toroid winding machine
ReplyDelete
ReplyDeleteThe melancholies are joined with inside tallness levels in setting of the bombs deplorably may happen. These sorts of pulling in powder centers are not obliged with a trademark folio so it has don't demonstrated the warm having impacts, handle with powder squash centers.toroid winding machine