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Products  |  Thermal Engineering and HVAC  |  Refrigeration and Air Conditioning Technology  |  ET 174
ET 174 Electrical Faults in Full Air Conditioning Systems Show data sheet (pdf file) Print page
Technical Description

Identifying electrical faults in air conditioning systems requires comprehensive knowledge. This knowledge includes the design and operation of the individual electrical components as well as the reading of circuit diagrams. ET 174 helps to acquire this knowledge.
  ET 174 demonstrates the electrical circuit of a complex full conditioning system with heat pump function. The control circuits are actually present. The components in the load circuits are simulated (e.g. compressor, heater, 4-way reversing valve).
  The air conditioning system with heat pump function cools in the summer and heats in the winter. During heating operation the defrost timer introduces a hot gas defrosting by briefly switching the 4-way reversing valve. At very low outer temperatures an electrical auxiliary heating is activated during heating operation. With low air humidity the hygrostat activates the humidifying function.
  Typical protection devices, such as circuit breaker and frost protection monitor, complete the electrical circuit. The operating state of the simulated components is indicated via lamps in the circuit diagram on the front panel.
  The simulation of 30 different faults, such as coil fracture in the motor or faulty relays, is possible. For fault identification the voltages or resistances at the lab jacks are checked with the multimeter. The

depiction of the circuit diagram on the front panel facilitates the allocation of the measuring points.
  The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments. 


Learning Objectives / Experiments

- Electrical design and operation of full conditioning

- Read and understand electrical circuit diagrams
- Design and operation of electrical components in

  an air conditioning system
  * start-up capacitor
  * start-up relay
  * operating capacitor
  * overheat protection
  * Heinemann circuit breaker
  * solenoid valve
  * defrost timer
  * float switch
  * thermostat
  * hygrostat
  * frost protection monitor
- Fault finding in electrical components
  * in idle state
  * under mains voltage


* Simulation of the electrical circuit of a complex

  conditioning system with humidifying and heat pump

* Investigation of key electrical components from air

  conditioning technology1
* Simulation of 30 faults

Alternative products
ET 144 -- Electrical Installation in Refrigeration Systems
ET 170 -- Electrical Faults in Simple Air Conditioning Systems
ET 171 -- Electrical Connection of Refrigerant Compressors
ET 172 -- Electrical Faults in Refrigerant Compressors
ET 340 -- Building Automation in Heating and Air Conditioning Systems
ET 930 -- Evaporator Control with Electronic Expansion Valve
[1] Experimental unit from the GUNT practical series for the training of mechatronics engineers for refrigeration
[2] Simulation of the electrical circuit of a complex conditioning system with humidifier and heat pump function for heating, cooling and humidifying
[3] Real control circuits with electrical components, simulated load circuits
[4] Electrical simulation of compressor, 2 fans (room air, outer air), 4-way reversing valve, auxiliary heating
[5] Humidifier with hygrostat, solenoid valve and float switch (pump simulated)
[6] Hot gas defrosting by switching the 4-way reversing valve
[7] Operating states of the simulated components indicated via lamps in the circuit diagram
[8] Circuit diagram depicted on the front panel
[9] Identification of 30 faults: multimeter measures voltages or resistances at the lab jacks 
Technical Data

Thermostat to switch between heating/cooling
- measuring range: 1...60C
Electrical compressor components
- start-up relay
- start-up capacitor

- operating capacitor
- overheat protection
- 2 pressure switches
Electrical components of room air fan
- start-up capacitor
- Heinemann circuit breaker
Humidifier components
- hygrostat: measuring range 30...95% r.h.
- float switch
- solenoid valve

- Heinemann circuit breaker
Defrosting components
- frost protection monitor: -10...12C
- timer: switching time 10...60min
Circuit breaker for auxiliary heating

Dimensions and Weight
l x w x h: 1000 x 400 x 850 mm
Weight: approx. 30 kg
Required for Operation
230V, 50/60Hz, 1 phase  or 120V, 60Hz, 1 phase
Scope of Delivery

1 experimental unit

1 multimeter

1 set of instructional material

Order Details

061.17400  ET 174  Electrical Faults in Full Air

                                Conditioning Systems

© 2005 G.U.N.T. Gerätebau GmbH