Результати проходження тесту
Which of the following is the minimum acceptable value of insulation resistance for High Voltage equipment?:
High Voltage systems rely on the installed protective equipment being able to interrupt any fault in the system. Throughout the system, the fault level has been calculated, and under no circumstances must the system be modified to exceed this fault level. What is meant by fault level?:
When there is a need to interrupt current flow in a High Voltage system it may be very difficult to quench the electrical arc, which is generated at the circuit breaker contacts. Which of the following among media is commonly found in High Voltage marine switchgear?:
A High Breaking Capacity fuse found in a Main High Voltage Switchboard will typically have fault level rating of:
“Protective discrimination” means the progressive grading of sizes, or tripping times of:
This is a typical emitter follower. What is the main reason for use of an emitter follower?:
The amplifier circuit is a common configuration used to amplify the difference in voltage between two input signals. In this case input 1 and 2. What is an amplifier called?:
Which of the functions shown is this operational amplifier circuit performing?:
Which function is this operational amplifier circuit performing?:
The figure shows a silicon controlled rectifier with a RC circuit connected in parallel. What is the purpose of the RC circuit?:
This is a parallel L-C circuit with a curve showing frequency – impedance characteristics. Which of the formulas gives the resonant frequency fo?:
Ordinary thyristors (SCR) must often be protected against reverse overvoltage transients, because even over-voltages of extremely short duration can destroy them. These SCRs have been given such over-voltage protection, but only one of them is correct. Which?:
These circuits are all active filters. Which of the circuits is a low-pass filter?:
Diodes are widely used in rectification, or the convention of alternating current to direct current. The sinusoidal input voltage V (in) is applied to the circuit shown. Which of the output voltages is correct?:
The circuit symbol is a driver for a solenoid (coil) of a solenoid valve S. What is the purpose of the diode IN 4 002 connected in parallel to the solenoid S?:
The diode shown performs which function?:
The circuit shown is a logic gate with two “high” input signals, A and B, and one output signal Q. Which type of logic function does the gate provide?:
The wheatstone resistance bridge is often used for measuring resistances in, for example, Pt 100 temperature sensors or strain gauges. This figure shows such a bridge. Under what conditions will the bridge be balanced? I.e. the current through the meter i(m) = 0.:
What function is this circuit performing?:
This graphical symbol is a logic gate. Which type of gate?:
An important quantity which is useful in circuit analysis is known as conductance G (Siemens). Which of the formulas express the conductance for this circuit?:
A 5 V DC source has an internal impedance of 0,2 ohms. When a load of 2,3 ohms is applied what voltage will be measured at the source terminals?:
What principle of measurement are viscosity controllers usually based upon?:
What is the maximum current that a 15 V, 3 Watt Zener diode can handle without damage?:
The inductance, which will induce an EMF of 1 Volt in a conductor, when the current is changing at a rate of 1 Amp per second, is defined as:
The typical current gain for a common emitter transistor is:
The instrument most widely used for testing of semiconductor diodes is:
A 6-Volt DC relay is to be used with a 12-Volt power supply. The relay requires a current of 0,1 Amp. What is the series resistance required?:
Some ships generate electrical power at 440 V, but then step up this voltage to supply specific electrical equipment. One common example, may be to feed a large bow thruster. Why is this done?:
When work must be done on High Voltage equipment, it is vital that the equipment is earthed (grounded) after isolation procedures have been carried out. Why is this?:
When selecting switchgear to work with High Voltage it is important to use an appropriate arcing medium. What is meant by arcing medium?:
Sometimes an early warning of failure in High Voltage switchboards may be an unpleasant smell. If the switchboard uses gas circuit breakers, which of the following may indicate a potential problem?:
A ship’s electrical system operates at 60 Hz, but when connected to shore supply it is supplied with 50 Hz. Which of the following would you expect?:
When starting three phase induction motors there is sometimes a need to use a star-delta starter. A star-delta starter exhibits the following characteristics while connected in a star.:
A 3-phase cage rotor induction motor requires protection by a time delay overload trip. What is the reason for this?:
A cable has a resistance of 100 milli-ohms. It supplies a 300 A load over a distance of 100 meters. What is the voltage drop along it’s length?:
Low voltage ships tend to have insulated neutral systems. What is the reason for this?:
Power is available at a three-phase motor starter, but nothing happens (at starter or motor) when the start button is operated. Which of the following is a likely cause?:
The continuity resistance of a 100 m long x 25 sq. mm cable (rated at 100 A) is to be checked. Which of the following results would you anticipate?:
When performing electrical testing of a three phase motor, insulation resistance measurements may be influenced by which of the following?:
A transformer overheats while taking a shore supply. Which is the likely cause?:
Continuity testing of a delta connected three phase induction motor yields the following results; U1-V1 = 4 Ohms, V1-W1 = 4 Ohms, W1-U1 = 4 Ohms. What is the value of continuity resistance for each winding i. e. U1-U2?:
When considering instrumentation systems, what is a typical symptom of a fault with the span of an instrument?:
Continuity testing of a delta connected three phase induction motor yields the following results: U-V = 3 Ohms, V-W = 3 Ohms, W-U = 6 Ohms. Which of the following is the likely condition?:
A 250 V contactor has been fitted to a 220 V supply. Which of the following symptoms might be observed?:
Routine maintenance insulation testing of a three-phase induction motor should cover which measurements?:
When measuring level of liquids with a conductivity level indicator, measurement is performed by:
When considering instrumentation systems, what is the meaning of the expression “dead-band”?:
What should be the healthy continuity resistance of a 220 V, 2,2 kW, 10 A heating element, when checked near to it’s rated operating temperature?:
A thermistor, which provides feedback for a thermal control system, is suspected to have failed. Assuming there is no available replacement, which of the following methods may be used to prove it has failed?:
A triac is used to provide temperature control of an oven. The galley complains that the oven only reaches approximately 50 % of demanded temperature. Which of the following is a likely cause?:
The coil of a 12 V, 120 mA DC relay must be connected across a 24 V supply. What action should be taken?:
A galley hot plate uses a Nichrome/Magnesium Oxide heating element, and is to be tested before being put into service for the first time. An insulation resistance test yields a reading of 0,3 M Ohm. Which action should be taken?:
What kind of electrolyte is used for Nickel-iron batteries?:
Two reference points for pressure exist, absolute zero and atmospheric pressure. What are pressures measured relative to absolute zero called:
A transformer rated at 22 kVA, 440/220 Volts, 60 Hz, is used to step down the voltage to a lighting system. The low tension voltage is to be kept constant at 220 Volts. What load impedance connected to the low-tension side will cause the transformer to be fully loaded?:
In the circuit diagram shown the starter connects between which terminals?:
What is the advantage of a transmitter with a narrow measurement range?:
Some automated control systems use a master controller and a slave controller. What is the meaning of “remote mode” related to a slave controller?:
When turning a cascade control system, which of the following actions should be done first?:
In the context of an automated process control system, what is understood by the expression Master Controller?:
In which of the following automated control processes will the time constant be of minor importance?:
In terms of automated control systems, what is typical for a continuous control system?:
Which of the following is typical for a feed-forward control system?:
In the context of an automated control system, which controller must be tuned first in a cascade control system?:
When measuring viscosity with a restricted flow viscometer, the preferred sensing device is:
The circuit diagrams illustrate four different methods of wiring between a Pt 100 temperature sensor and its signal processing electronics. Which of the wiring methods gives the best measuring accuracy?:
In what kind of measuring equipment might we find a Bourdon-tube?:
Which of the following detectors is preferred for detecting smoke from fire?:
Which type of temperature sensor is used in this temperature measuring system shown?:
Which electronic component or system is this graphical symbol illustrating?:
Which device does this graphical symbol illustrate?: