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SACA C-202 ELECTRIC MOTOR CONTROL
SYSTEMS EXAM STUDY GUIDE 2026
โ What will happen if the terminals of a blowout coil are reversed? Answer: Theoretically, the motor action of the arc will be in the opposite direction. โ Multiple stop buttons are electrically wired in _________ Answer: series โ Main or subassembly line conveyors use sequence control. Answer: true โ The operation of the overload protection ____ the control circuit. Answer: opens โ You should never wire in a set of normally closed contacts in a series with thecoil of the same device. Answer: true โ The larger contactor sizes are used to provide remote control of relatively high-current circuits where it is too expensive to run the power leads to the remote controlling location Answer: true
โ What does IEC stand for? Answer: International Electrotechnical Commission โ If the HOA switch is set in the off position, ____ current can flow to the coil of the starter. Answer: on โ Which of the following factors will affect the selection of a timing relay. a. Type of power supply b. contact ratings c. timer contact arrangement d. temperature range e. dimensions Answer: all of them โ A pneumatic timer is adjusted by positioning a needle valve to vary the degree of orifice restriction. Answer: true โ An HOA switch is a two position selector switch Answer: false โ When there are several timers that meet the requirements of a given application, it is advisable to select the timer with the ____. Answer: smallest number of operating parts โ An advantage of using a two-wire control device is because automatic controls may be used to control a motor or an operation without requiring the presence of an operator. Answer: true
โ The symbol for a __ switch represents a bimetal helix. Answer: temperature โ The addition of a control relay to a jogging circuit provides even greater control of the motor drive than the use of a jogging circuit alone. Answer: true โ It is sometimes desirable to operate push buttons or other control devices at some voltage higher than the motor voltage Answer: false โ The equipment ground can be _______. Answer: green and bare โ A control relay is an electrically operated switch. Answer: true โ What type of device is used to suppress voltage spikes in relay circuits? Answer: Transient suppressor or Metal oxide varistor โ Three-wire control prevents the restarting of machinery when power is restored. Answer: true โ Timed contacts are either normally open or normally closed Answer: true
โ Typical control voltages are 120 and ____ volts Answer: 24 โ Multiple push-button stations are used to control conveyor motors ____. Answer:. on large shipping and receiving freight docks โ If the available power is 208V-3 phase, and the control circuit is wired phase tophase, what is the control voltage? _____ volts. Answer: 208 โ Pneumatic timers have good repeat accuracy. Answer: true โ Electronic Off-delay timers must have power applied ____ topermit the timing circuit to operate Answer: at all times โ Motors draw half as much current on high voltages as they do on low voltages Answer: true โ The use of a selector switch in the control circuit to obtain jogging requires a three-element control station with start and stop controls and a ____ switch. Answer: selector switch โ Electrical symbols usually conform to which standard? Answer: NEMA
โ The conventional three-wire, push-button control circuit may be extended by the addition of one or more push-button control stations. Answer: true โ Ladder diagrams are sometimes referred to as elementary diagrams Answer: true โ The greatest advantage of relays with mechanicalcontacts is that they are resistant to shock and vibration Answer: false โ The term inching is often used when referring to across-the-line starters. Answer: false โ Jogging is defined by ____ as "the quickly repeated closure of a circuit to start a motor from rest for the purpose of accomplishing small movements of the driven machine." Answer: nema โ When components are used to perform the function of stop, they are generally wired ____ with the motor starter coil. Answer: n ormally closed and connected in series โ The motor may be started or stopped from a number of separate stations by connecting all start buttons in parallel and ____ stop buttons in series. Answer: all
โ A selector switch and the automatic pilot device can control a motor directly if their contacts are large enough to pass safely the full-load current of the motor. However, the contact capacity of these devices is usually not large enough for large motors. Answer: true โ List two (2) other names that are used in place of the term "schematic" Answer: Elementary and Ladder โ Select the definition of a wiring diagram. (Be thorough!!!) Answer: Is a pictorial diagram. It shows the physical layout of all the equipment and allthe interconnecting wiring. โ A triac is used to connect the load to the line in a solid-state relay intended to control an AC load. Answer: true โ The movable contact for a normally closed switch is drawn __. Answer: above and touching the stationary contact. โ A selector push button can be used to obtain jogging Answer: true โ It is necessary to restart a motor after it has been stopped by a three-wire control circuit with ____ protection Answer: low voltage โ A two-wire control may be a toggle switch Answer: true
โ When a jogging circuit is used, the starter can be energized only as long as the jog button is depressed Answer: true โ Control relays are small magnetic switches used on simple branch circuits to control complex wiring system operations. Answer: true โ When the switch is set in the hand position, contacts 1 and 2 are closed, and contacts 3 and 4 are ____. Answer: open โ Schematics are always drawn to show components in their de- energized or off state Answer: true โ A hand-off automatic switch may be a stand alone control or incorporated into a start-stop push button station. Answer: true โ If the available power is 480/277-3 phase, and the control circuit is wired fromphase to ground, what is the control voltage? _____ volts Answer: 277 โ Starters, contactors, and ____ are similar in construction and operation Answer: relays โ No-voltage protection protects ____. Answer: both the operator and the equipment
โ Two-wire control ____. Answer: provides no-voltage release or low-voltage release โ Most of the relays used in machine tool controlhave double-break contacts. Answer: true โ The exact timing value for any position within the timing range must be ____. Answer: found by trial and error โ The most common coil symbol used in schematic diagrams is the rectangle Answer: false โ The control circuit consists of the main contacts and the overload heaters to the motor Answer: false โ Selector switches often contain multiple sets of contacts. Answer: true โ When reading a schematic diagram? Answer: Are the control components shown as they should be when the machine is turned off or de-energized
โ When configuring separate control wiring, the maintenance technician must ensure that the proper connections are made. Answer: true โ Line diagrams include all of the devices in the system and show the physical relationships between the devices. Answer: false โ Nontimed contacts are controlled directly by thetimer coil, as in a(n) ____ control relay. Answer: general-purpose โ When a jogging circuit is used, the machine operator has ____ control of the motor drive. Answer: instantaneous โ Sirens, horns, and loud buzzers may be used in production systems to call attention to malfunctions Answer: true โ What are the advantages of a mechanically held relay? Answer: The current is not continually applied to the coils of the relay, thus conserving energy. b. It is absolutely quiet in operation. c. The relay need not be reset when the power returns. d. The circuit continuity is maintained during a power failure. e. All of the above.(Correct Answer)
โ A mechanically held or latching relay is operated by electromagnets. Answer: true โ Two-wire controls may be connected to operating coils of magnetic switches Answer: true โ The most standardized set of symbols in the U.S. is provided by the NEMA. Answer: true โ Relays are ____________ operated switches. Answer: Electrically โ Anothername for a schematic diagram is a wiring diagram. Answer: false โ What is the first action when the start button of a three-wire control circuit is pushed? Answer: The circuit is completed through the coil. โ When jogging with a control relay on a reversing starter, while the relay is energized, ____. Answer: either the forward or the reverse starter will also remain energized โ
