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Maine-Electrical Master Online Practice Test

These are actual questions from our online practice test.

We have included a question from each chapter of the test. Every question will be multiple choice. The answers are not included with the sample.

Sample Questions

 # Chapter Title Question 1 Capacity Factor/ Unit Load Calculations 1/Demand Factor /Dielectric mandy note: go to https://en.wikipedia.org/wiki/Dielectric_spectroscopy for next questions 2 Distribution Feeder Regulation/Delta/Delta wye Transformers /Voltage Drop/Voltage Divider/Voltage Regulation/Current Divider One case of voltage regulation is in a transformer. The unideal components of the transformer cause a change in voltage when current flows. Under no load, when no current flows through the secondary coils, Vnl is given by the ideal model, where VS = VP*NS/NP. Looking at the equivalent circuit and neglecting the shunt components, as is a reasonable approximation, one can refer all resistance and reactance to the secondary side and clearly see that the secondary voltage at no load will indeed be given by the ideal model. When the transformer delivers full load, a voltage drop occurs over the winding resistance, causing the terminal voltage across the load to be lower than anticipated. This leads to a ___________ voltage regulation which must be considered in use of the transformer. 3 Theory Incidence matrix: The  ${displaystyle n_{t} imes n_{f}}$  matrix  ${displaystyle mathbf {A_{a}} }$  is called node-to-________ incidence matrix for the matrix elements  ${displaystyle a_{ij}}$  being ${displaystyle a_{ij}={egin{cases}1,&{ ext{if flow }}j{ ext{ leaves node }}i-1,&{ ext{if flow }}j{ ext{ enters node }}i,&{ ext{if flow }}j{ ext{ is not incident with node }}iend{cases}}}$ A reference or datum node  ${displaystyle P_{0}}$  is introduced to represent the environment and connected to all dynamic nodes and terminals. The  ${displaystyle (n_{t}-1) imes n_{f}}$  matrix  ${displaystyle mathbf {A} }$ , where the row that contains the elements  ${displaystyle a_{0j}}$  of the reference node  ${displaystyle P_{0}}$  is eliminated, is called reduced incidence matrix. The conservation laws (KCL) in vector-matrix form: ${displaystyle mathbf {A} mathbf {F} =mathbf {0} }$ The uniqueness condition for the potentials (KVL) in vector-matrix form: ${displaystyle mathbf {W} =mathbf {A^{T}} mathbf {w} }$ where  ${displaystyle w_{k}}$  are the absolute potentials at the nodes to the reference node  ${displaystyle P_{0}}$ . Proof: Using KVL: {displaystyle {egin{aligned}mathbf {W^{T}} mathbf {F} =mathbf {(A^{T}w)^{T}} mathbf {F} =mathbf {(w^{T}A)} mathbf {F} =mathbf {w^{T}AF} =mathbf {0} end{aligned}}} because  ${displaystyle mathbf {AF} =mathbf {0} }$  by KCL. So: ${displaystyle sum _{k=1}^{b}W_{k}F_{k}=mathbf {W^{T}} mathbf {F} =0}$ 4 Conductor Sizing/Protection Calculations/AC Power Plugs/Sockets A blade connector is a type of single wire connection using a flat conductive blade which is inserted into a blade receptacle. Usually both blade connector and blade receptacle have wires attached to them either through of the wire to the blade or ______________ of the blade to the wire. In some cases the blade is an integral manufactured part of a component (such as a switch or a speaker unit), and a blade receptacle is pushed onto the blade to form a connection. 5 MIL-STD-1553/ACCC Conductor/Motors/Transformers/Circuit Breaker/Brushed DC Electric Motor/Short Circuit MIL-STD-1553B does not specify the length of the bus. However, the maximum length of bus is directly related to the gauge of the cable conductor and time delay of the transmitted signal. A smaller conductor attenuates the signal more than a larger conductor. Typical propagation delay for a 1553B cable is 1.6 _____________ per foot. Thus, the end-to-end 100-foot bus (30 m) would have a 160 nanosecond propagation delay, which is equal to the average rise time of a 1553B signal. According to MIL-HDBK-1553A, when a signal's propagation delay time is more than 50% of the rise or fall time, it is necessary to consider transmission line effects. This delay time is proportional to the distance propagated. 6 Junction Boxes/Raceways/Conduit Bodies/Reclosers/Multiway Switching/Camlock If the PVC coating is UL listed as the primary corrosion protection, does that mean the conduit complies with NEMA RN-1? 7 AC/DC/Capacitance/Inductor/SWER 1 Inductors in a parallel configuration each have the same potential difference (voltage). To find their total equivalent inductance (Leq): ${displaystyle {frac {1}{L_{mathrm {eq} }}}={frac {1}{L_{1}}}+{frac {1}{L_{2}}}+cdots +{frac {1}{L_{n}}}}$ The current through inductors in series stays the same, but the voltage across each inductor can be different. The sum of the potential differences (voltage) is equal to the total voltage. To find their total inductance: ${displaystyle L_{mathrm {eq} }=L_{1}+L_{2}+cdots +L_{n},!}$ These simple relationships hold true only when there is no mutual coupling of magnetic fields between individual inductors. 8 Ground/Earthing System/Three-Phase An ungrounded electrical box, appliance, power tool, or extension cord could become a danger if there is no path to ground, except through you. Without a ground wire, your body may complete the ground path and you may be shocked or electrocuted. In older homes with cloth wrapped wire or in homes with knob and ____________ wiring, this is the case. Newer appliances and some tools come equipped with a three-pronged cord, incorporating a ground for protection. 9 HV Circuit Breaker Testing/Unit Load Calculations 2/Service Load Calculations/Optional Methods/SWER 2/Motor Constant Where should you mount your transducer? You should look for an easily attachable place where your transducer will move in conjunction with the interrupter(s). You should also try to mount the transducer to a solid piece of metal that won’t vibrate during operation of the circuit breaker. The closer you are to the interrupter without mechanical linkages in between, the more accurate your travel ___________ will become. Once a transducer mounting spot is established, you should continue to test it at this spot for accurate trending purposes. 10 Inductance/Impedance/Connectors Resistance ${displaystyle scriptstyle R}$ is the real part of impedance; a device with a purely resistive impedance exhibits no phase shift between the voltage and current. ${displaystyle R=|Z|cos { heta }quad }$ Reactance ${displaystyle scriptstyle X}$ is the imaginary part of the impedance; a component with a finite reactance induces a phase shift ${displaystyle scriptstyle heta }$ between the voltage across it and the current through it. ${displaystyle X=|Z|sin { heta }quad }$ A purely reactive component is distinguished by the sinusoidal voltage across the component being in quadrature with the sinusoidal current through the component. This implies that the component alternately absorbs energy from the circuit and then returns energy to the circuit. A pure reactance ___________ dissipate any power. 11 OSHA/Asbestos/Code of Federal Regulations, Title 29, Part 1926 A revision (marker) is shown on the completed set of working drawings by _______________. 12 Employees/Contractors/Insurance/Safety/Training As part of the safety training process, contractors' supervisors are required to conduct "toolbox" and "tailgate" safety meeting. How often must these be held? 13 Safety/Dig Alert/Fire Extinguishers AL 811 Dig Alert, must be notified of site excavation at least ___________ days but not more than _______. 14 Mathematics/Calculations/Formulas 10 × (1/10) = 10 x 0.1 = _________