Controls 3 Exam

Which of the following best describes an ECM?

A dc, three-phase motor with a permanent magnet rotor

The biggest difference in design between a synchronous motor and an induction motor is the _______

DC electromagnetic rotor

The primary cause of motor insulation failure is _______.

Motor overheating

Which of the following types of relay has normally open contacts that close with high inrush current and open once the motor reaches running speed?

Current relay

In which two ways can the stator phase coils in a three-phase induction motor be connected?

Delta or wye

Where would you find the rated hp, the speed, the full load amperage, and the date code of a motor?

Nameplate

The motor's direction of rotation is viewed from the vantage point of _______.

The drive end of the motor

You determine which wires are for which speed tap on a multispeed PSC direct drive motor by the _______.

Wiring schematic colour codes

The purpose of an overload device is _______.

To protect the motor from overheating

What is the difference between a wound rotor motor and a squirrel cage induction motor?

The wound rotor motor has insulated windings

When removing or replacing a capacitor, you should always short out the terminals to drain any stored charge.

True

Which of the following types of relay uses transistors, diodes, and triacs to break the start windings circuit at the correct time?

Solid-state relay

Which of the following types of relay has a normally closed set of start winding contacts that are opened by the relay coil after the motor has started?

Potential relay

What are the two main parts of an electric motor?

Stator and rotor

The easiest way to tell if motor bearings require lubrication is by the _______.

Grease fittings

What does it mean to isolate a component while preparing for resistance measurments?

At least one wire must be removed from the component that shall be measured.

Based on the oven circuit drawn on the board on our classes (and also found in your chapter 1 of unit 12), what method of ignition proving does the manufacturer use for the main oven combustion?

The manufacturer expects that a person will be present to view and monitor the flame.  If no flame is present then the person should shut off the gas.

A _______ is a semiconductor device used to switch or amplify signals.

Transistor

Low-water cutoff, gas-pressure switch, and flow switch belong to the _______ section of the control system.

Limit and safety controllers

Sealed bellows controls operate on the principle of _______.

The thermal expansion of liquids

Position and location are important factors for thermostat installation.

True

A/an _______ is a backup safety designed to shut off the burner if the temperature of the water in the heater exceeds 200 °F.

ECO

Thermocouples and thermopiles operate on the principle of _______.

The thermoelectric effect

The temperature disc, bimetallic strip, and rod-and-tube controls all operate on the principle of _______.

The thermal expansion of solids

Solenoids operate on the principle of _______.

Electromagnetism

A thermocouple is considered a combustion safety control.

True

Redundant gas valves can be (adapted by a/an) _______ to give them modulating operation.

Electric stepper motor

SCR, TRIAC, and DIAC are _______ types of electronic devices are

Thyristor

On an electric oven safety valve, the HSI must warm up sufficiently before enough electricity can pass to open the gas valve.

True

The servo regulator integrated into a combination gas valve functions as a/an _______.

Appliance regulator

Non-integrated ignition control modules designed for intermittent pilot, direct spark, or hot surface ignition also manage all of the other appliance activities, such as humidistat, electronic filters, heating pumps, or fans.

False

A/An _______ is used to sense combustion air or flue gas flow on any appliance that incorporates a fan or blower.

Air-proving switch

A seismic valve resets automatically once vibration stops.

False

What is a DIP switch?

A manual electric switch that is packaged with others in a group

The thermostat, operating aquastat, and operating pressuretrol belong to the _______ section of the control system.

Operating controllers

Which of the following multi-stage thermostat methods employs algorithms to anticipate demand?

Rate-of-change staging

Cable release fire suppression gas valves can only be activated manually.

False

Mercury is used in capillary tubes suitable for high temperature operations.

True

An operating aquastat is _______.

An NC switch that shuts off the gas supply when the temperature setpoint is reached

A/an _______ acts as extra protection on a redundant gas valve.

Second automatic shut-off valve

Pilot-operated solenoid valves use pressure differentials to assist the plunger to open and close the main valve.

True

Which of the following combustion safety controls works on the principle of flame ionization?

Flame rod (flame rectifier)

A _______ is a semiconductor device that allows the flow of current in only one direction.

Diode

Electronic thermostats control temperature swing overshoot via _______.

CPH

Which of the following control components produce electricity when heated?

Thermocouple

The purpose of an operating pressuretrol is _______.

To stop the boiler if the steam pressure gets too high

A rod-and-tube (e.g., Unitrol) valve would typically be installed on _______ type of gas appliance.

A gas water heater

One advantage of a smart valve is that it uses a regular 110-V ac HSI.

False

A PTC thermistor decreases its resistance with an increase in temperature.

False

Thermostats should be placed on a wall that connects with the exterior of the building.

False

A thyristor is different from a transistor in that it only needs a pulse signal to make it conduct and will continue to conduct without needing further signals.

True

Most electronic thermostats come preset at a CPH setting of _______.

4 to 5

Indicate whether the given statement is true or false. Solid-state electronic devices are made up of electro-mechanical components that move.

False

A _______ is a semiconductor device that changes its electrical resistance with a change in temperature.

Thermistor

The air surrounding the blower section of the furnace has become too hot then what should occur?

An auxiliary limit should shut down the burner

If a forced air furnace's heat exchanger becomes too hot, then what should occur?

The high limit should shut down the burner

What will occur if a water heater's aquastat neglects to shut down the burner?

The water will get too hot

What will occur with insufficient air passing through a forced air furnace's blower and associated system?

The furnace will overheat

If a storage water heater's water becomes too hot then what should occur?

The T&P should relieve water into the basement

Which setting should the multimeter be on when testing the flame sensing circuit?

µA dc

Integrated electronic control boards have replaced most time delay relays.

True

It is best to use a _______ electrical drawing to determine how current flows through the various parts of a circuit.

Schematic diagram

The purpose of the control modules safe start check is _______.

To confirm there is not already an existing flame

The term _______ refers to matching the polarity of the primary and secondary sides of a transformer.

Phasing

For ac circuits, the term _______ refers to the difference between the hot, neutral wire and the ground wire.

Polarization

For this relay connected to a 120-V circuit, what would be the AFL rating for the NC contacts?

13.8 A

When checking for transformer phasing, you should a voltage reading of _______ between the 120 V ac hot and ungrounded side of the secondary?

96 V ac

The sine waves below represent primary and secondary transformer circuits that are in phase.

False

_______ are the most common auxiliary devices found in control systems.

Switches

A _______ electrical drawing is considered to be like a "map" of an electrical circuit.

Wiring diagram

Refer to the DIP table below to determine the "HEAT "OFF" DELAY" setting for the DIP switch configuration given:

180 sec

Which of the following describes the operation of a flame rollout switch?

NC switch that opens on flame rollout

A schematic diagram is also known as a _______.

Ladder diagram

The sequence of operations for all components connected to an IFC can be determined from the wiring diagrams.

False

The left hand side of a ladder diagram represents the incoming voltage.

True

What is one reason for using an economizer on a rooftop unit?

For ventilation

What does DDC represent in HVAC controls?

Direct digital controls

What does EMS represent in HVAC controls?

Energy management system