HVAC Electrical ESCO

Relays are generally used to control inductive loads up to ___ amps. а. 100. b. 10. C. 25. d. 50.

C. 25.

When checking the windings of a three phase motor: a. All three terminals should show different readings. b. The pair with the highest resistance will indicate the other is common. C. All three terminals should show the same resistance. d. It is usually cheaper to replace a three phase motor than to test it.

C. All three terminals should show the same resistance.

To change direction of rotation of a three phase motor: a. The motor must be replaced. b. Change the position of all three supply wires. C. Change the position of any two supply wires. d. The rotation of three phase motors cannot be changed

C. Change the position of any two supply wires.

A solenoid valve coil operates on the principle of: a. Pressure differential. b. Temperature differential. C. Electromagnetism. d. Time and temperature.

C. Electromagnetism.

A typical thermocouple used on a gas furnace can: a. Generate a small AC electrical current. b. Be used to power a shaded pole motor. C. Generate a small DC electrical current. d. Generate up to 1 volt.

C. Generate a small DC electrical current.

The capacitor start-capacitor run (CSCR) motor provides: a. High running and low starting torque. b. Medium running and high starting torque. C. High starting and running torque. d. High running and medium starting torque.

C. High starting and running torque.

When testing the windings of a single phase motor: a. The pair of terminals with the highest resistance will indicate that the other terminal is the start. b. The common to start terminals show the lowest resistance. C. The common to run terminals show the lowest resistance. d. The start to run terminals show the lowest resistance.

C. The common to run terminals show the lowest resistance.

Which of the following is generally considered to be within the maximum allowable (plus or minus) supply voltage variation? a. 5%. b. 15%. C. 20%. d. 30%.

a. 5%.

A diode is used to: a. Control the direction of electron flow. b. Increases inductive reactance. C. Convert DC current to AC current. d. Increase or decrease frequency.

a. Control the direction of electron flow.

Resistance can be calculated by: a. E÷l b. W÷E C. C. E squared x W d. I÷E

a. E÷l

The thermal overload contacts on a line starter are usually ________ reset. a. Manual. b. Automatic. c. Thermal. d. Time delay.

a. Manual.

Which meter is used to bench check a motor for shorts or open windings? a. Ohmmeter. b. Voltmeter. C. Ammeter. d. Wattmeter.

a. Ohmmeter.

Which of the following meters must use its internal power to check a load or circuit? a. Ohmmeter. b. Voltmeter . c. Ammeter. d. Wattmeter

a. Ohmmeter.

Impededance a. Opposition to alternating current flow. b. Electrical pressure. C. Amperage. d. Voltage applied to the circuit.

a. Opposition to alternating current flow. (All types of resistance combined)

Resistance is: a. Opposition to current flow. b. Electrical pressure causing voltage flow. c. Enables amperage flow. d. Opposition to alternating current only.

a. Opposition to current flow.

The ________ drawing illustrates where the components are located in small appliances. a. Pictorial. b. Schematic. c. Ladder. d. Outside.

a. Pictorial.

In electrical wiring, a black colored wire in an alternating current circuit usually indicates: a. The hot conductor. b. The neutral conductor. C. The ground conductor. d. The safety conductor.

a. The hot conductor.

A three phase load requires a minimum of: a. Three supply lines. b. Two supply lines and a ground. C. Three supply lines and a neutral. d. Two supply lines.

a. Three supply lines.

On an electronic oil safety switch what changes the pressure signal to electrical signal. a. Transducer. b. The circuit board. c. The bellows. d. Electronic processor.

a. Transducer.

Which of the following is the correct formula for determining wattage in an electrical circuit? a. W= Ex| b. W = E/R c. W= 1/R d. W= ExR

a. W= Ex|

Utility companies usually supply residential homes with _____ service. a. 115v, single phase, three wire. b. 240v, single phase, three wire. C. 240v, three phase, three wire. d. 480v, three phase, three wire.

b. 240v, single phase, three wire.

One horsepower is equal to a. 3415. b. 746. c. 1200. d. 208.

b. 746.

An electron has: a. No charge. b. A negative charge. c. A positive charge. d. Neutral charge.

b. A negative charge.

Contactors are rated according to the maximum amperage through the: a. Coil. b. Contacts. c. Thermostat. d. Fuse.

b. Contacts.

Which of the following statements about current is true? a. Current flow is the same as voltage. b. Current flow will increase when voltage increases. c. Current flow will increase when resistance increases. d. Current flow will decrease when voltage increases.

b. Current flow will increase when voltage increases.

When the temperature of a negative temperature coefficient (NTC) thermistor increases, its resistance will: a. Increase. b. Decrease. c. Remain the same. d. Increase proportionately to the Delta T.

b. Decrease.

Which of the following motors is most energy efficient: a. SIRC. b. ECM. C. PSC. d. Shaded pole.

b. ECM.

When testing a motor with an ohmmeter, th following measurements are recorded; Common to run 4 ohms, common to start 6.2 ohms, run to start 10.2 ohms, and common to ground 20.4 ohms: a. Good safety ground b. Grounded condition. C. Open in the winding. d. Locked rotor condition.

b. Grounded condition.

The symbol for current is: a. E b. I c. R d. W

b. I

Capacitors are always connected start winding: a. In parallel. b. In series. C. Through a relay. d. Through a diode.

b. In series.

If the conductor in an AC circuit is wound into a coil, the resulting EMF opposes the supply voltage. This opposition is called: a. Capacitive resistance. b. Inductive resistance. C. Conductance. d. Influence.

b. Inductive resistance.

What connects to the terminals T1, T2, & T3 on a contactor or motor starter? a. Power supply connections. b. Load connections. C. Coil connections and ground. d. Start/stop leads.

b. Load connections.

When testing a capacitor with an analog or digital ohmmeter, the meter should: a. Show no deflection or resistance and remain on an infinite reading. b. Measure low resistance then return to high reading. c. Display a zero measurement and stay there/ d. Measure a precise resistan@s and stay there.

b. Measure low resistance then return to high reading.

Single phase motor speed is determined by the: a. The number of coils in the stator. b. Number of stator poles. C. Supply voltage. d. The circumference of the rotor.

b. Number of stator poles.

Like Charges a. Attract one another. b. Repel each other. c. Are negative. d. Are positive.

b. Repel each other.

If contacts become badly pitted, it is acceptable to: a. Sand the contacts. b. Replace the contacts or control. C. File the contacts. d. Replace the contacts or control with a solid state relay.

b. Replace the contacts or control.

When resistors are wired in parallel: a. The current through any one resistor will be the same as the total circuit current. b. The voltage drop across each resistor will be the same as the applied source voltage. C. The voltage drop across each resistor will depend on the value of each resistor. d. The total resistance is determined by adding the values of each resistor

b. The voltage drop across each resistor will be the same as the applied source voltage.

To discharge a capacitor prior to ohmmeter testing: a. Use a screwdriver across the capacitor terminals. b. Use a 15,000 or 20,000 ohm, 2 to 5 watt resistor across the terminals. C. Touch the terminals with your bare fingers. d. Use a 5,000 ohm, 2 to 5 watt resistor across the terminals

b. Use a 15,000 or 20,000 ohm, 2 to 5 watt resistor across the terminals.

Transformers are rated according to: a. VA at the primary. b. VA at the secondary. C.bOhms at the primary. d. Ohms at the secondary

b. VA at the secondary.

A step up transformer increases. a. Power. b. Voltage. C. Resistance. d. Amperage.

b. Voltage.

Any material that will readily release electron called: a. An insulator. b. conductor. c. A resistance. d. A neutron.

b. conductor.

The voltage to ground of a "high leg" or "stinger leg" on a three phase open Delta system will be approximately: a. 240 volts. b. 220 volts. c. 208 volts. d. 120 volts.

c. 208 volts.

A transformer has 1000 turns of wire in the primary coil and 500 turns in the secondary coil. If 120 volts are applied, the output voltage will be: a. 120 KV. b. 620 volts. c. 60 volts. d. 240 volts.

c. 60 volts.

With a motor running at full load, voltmeter leads are placed on L1 and T1 terminals of the contactor. The voltmeter indicates no measurable voltage. This is an indication of: a. No voltage to the motor. b. Excessive resistance in the contacts. c. Good clean contacts. d. This not a valid test.

c. Good clean contacts.

The safety ground conductor is usually color coded: a. Red or white. b. Black or white. c. Green or bare. d. White or bare.

c. Green or bare.

What would be the result, if a 24 volt, 20 - ohm low voltage contactor coil were wired in series with a 24 volt, 200-ohm control relay coil? a. Neither the contactor nor control relay would operate. b. Only the control relay would operate. c. Only the contactor would operate. d. Both the contactor and control relay would operate.

c. Only the contactor would operate.

The electric meter on a house measures the passing through it. a. Voltage. b. Amperage. c. Wattage. d. Resistance.

c. Wattage.

What is the minimum number of wires required between two start/stop push button controls: a. Depends on the design. b. 1. C. 2. d. 3.

d. 3.

Which of the following is an acceptable temporary replacement for a run capacitor rated at 35MFD @ 440VAC: a. 50 MFD @ 370VAC. b. 47.5 MFD @ 440 VAC. C. Two 20 MFD @ 440 VAC in series. d. 37.5 MFD @ 440 VAC.

d. 37.5 MFD @ 440 VAC.

An ohmmeter should never be connected to: a. A resistor until it has been checked by other means. b. A coil or a winding of a compressor. c. A motor that has a grounded condition. d. A charged capacitor until it has been discharged.

d. A charged capacitor until it has been discharged.

A is commonly used on a single phase capacitor start fractional horse power compressor motor to disconnect the start winding after the motor starts. a. Lock out relay. b. NTC thermistor. C. Kinetic relay. d. Current relay.

d. Current relay.

Which of the following would be considered ar inductive load? a. Electrical heat strip. b. Start capacitor. C. Solid state relay. d. Electric motor.

d. Electric motor.

Direct Digital Control (DDC) is: a. An electronic control that must be manually adjusted. b. A digital control for controlling the electron flow in a series circuit. C. A digital control for controlling the electron flow in a parallel circuit. d. Electronic controls use for equipment operation and monitoring.

d. Electronic controls use for equipment operation and monitoring.

The total resistance of a parallel circuit will be: a. The sum of all resistance. b. Equal to the largest resistance. c. Equal to the smallest resistance. d. Less than the smallest resistance.

d. Less than the smallest resistance.

A device with overload protection used to control a motor is a: a. Relay. b. Contactor. c. Selenium rectifier. d. Line starter.

d. Line starter.

Capacitors are rated in: a. Amps & volts. b. Microfarads & watts. C. Volts & ohms. d. Microfarads & volts.

d. Microfarads & volts.

A transducer can create a signal based on: a. Time. b. Turbulence. c. The specific gravity of the refrigerant. d. Pressure.

d. Pressure.

An electronically commutated motor (ECM) is designed to: a. Maintain a constant velocity. b. Have low starting torque. C. Operates at lower static pressure than axial fan motors. d. Provide proper air flow under various conditions.

d. Provide proper air flow under various conditions.

What is the term used to describe the output side of a transformer? a. Low inductive side. b. High inductive side. c. Primary side. d. Secondary side.

d. Secondary side.

Excessive current can be caused by: a. Oversized wiring. b. Undersized fuse. c. Selenium rectifier. d. Short circuit.

d. Short circuit.

Which of the following materials would be best suited for use as a semi-conductor? a. Copper. b. Bakelite. C. Aluminum. d. Silicon.

d. Silicon.

A capacitor analyzer is designed to read: a. The percentage of leakage. b. The capacitor voltage. c. The capacitive resistance of a capacitor. d. The capacitance of a capacitor.

d. The capacitance of a capacitor.

Current flow is: a. Flow of voltage in a circuit. b. The impedance of a circuit. c. The inductive reactance of the circuit. d. The flow of electrons in the circuit.

d. The flow of electrons in the circuit.

Fuses are sized by: a. Amps & watts. b. Volts & watts. C. Watts & ohms. d. Volts & amps.

d. Volts & amps.