Category Archives for Solenoids and Relays

Transformers for Low-Voltage Controls

The use of low-voltage control systems is becoming more widespread as the demand for residential air conditioning increases. This necessitates the use of a transformer for voltage reduction, normally to 24 V. The selection of a transformer is not accomplished … Continue reading

05. January 2011 by admin
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Hot-Gas Defrost Service Solenoid Valve

Several piping arrangements are used for hotgas defrost systems, one of which is shown in Fig. 6-25. A portion of the compressor discharge gas is passed through the solenoid valve into the evaporator. The solenoid valve may be controlled either … Continue reading

05. January 2011 by admin
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Suction-Line Service Solenoid Valve

There are several applications, particularly on suction lines, where pressure drops in the range of 2 to 4 lb/in.2 (psi) cannot be tolerated. Therefore, only valves that are capable of opening at very low pressure drops are suitable for this … Continue reading

05. January 2011 by admin
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Liquid-Line Service Solenoid Valve

The primary purpose of a solenoid valve in a refrigerant liquid line is to prevent flow into the evaporator during the off cycle. On multiple systems, a solenoid valve may be used in each liquid line leading to the individual … Continue reading

05. January 2011 by admin
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Solenoid Valves Principles of Operation

Solenoid valve operation is based on the theory of the electromagnets. The solenoid valve coil sets up a magnetic field when electrical current is flowing through it. If a magnetic metal, such as iron or steel, is introduced into the … Continue reading

05. January 2011 by admin
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HVAC Solenoid Valves

The primary purpose of an electrically operated solenoid valve is to control automatically the flow of fluids, liquid or gas. There are two basic types of solenoid valves. The most common is the normally closed (NC) type, in which the … Continue reading

05. January 2011 by admin
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HVAC Power Relays

A heavy-duty power relay that operates from solenoid action is shown in Fig. 6-20. In this device, a spring pulls the solenoid core, or armature, away from the electrical contact when the current is off. When current flows, the armature … Continue reading

05. January 2011 by admin
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HVAC Solenoid

A magnetic field seeks the path of minimum reluctance, just as an electric current seeks the path of least resistance. Reluctance and resistance are related. Resistance refers to the opposition to current flow in a circuit. Reluctance refers to the … Continue reading

05. January 2011 by admin
Categories: Solenoids and Relays | Tags: | Leave a comment