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Relays and Contactors
Published in Joseph E. Fleckenstein, Three-Phase Electrical Power, 2017
A contactor is also called an “electromagnetic contactor,” although it is most often merely called a “contactor.” Contactors have a coil and a set of contacts arranged in a configuration that approximates what is found in control relays. When voltage is applied to the coil of a contactor, the contactor’s contacts are closed to deliver power to the controlled electrical gear. The main difference between a relay and a contactor is that the latter is used to connect and interrupt higher levels of power. Typically, contactors control power to electrical gear as motors, heaters, lighting, and capacitor banks. Contactors are required in those applications where electrical power must be repeatedly applied and subsequently interrupted. Control of power to the very largest types of electrical gear is controlled by circuit breakers and not contactors. One significant difference between contactors and circuit breakers is that circuit breakers are designed to interrupt short circuit currents but contactors do not have that capability.
HVAC Basics
Published in Herbert W. Stanford, Adam F. Spach, Analysis and Design of Heating, Ventilating, and Air-Conditioning Systems, 2019
Herbert W. Stanford, Adam F. Spach
A contactor is an electrically operated switch, a large relay in effect, which can be made to switch a motor, heater bank, capacitor bank, and so on, on and off directly or by a remote controller, such as a thermostat, humidistat, timer, pilot devices, or any other protective devices. Although it is a switch, a contactor is designed to interrupt an electric current repeatedly and frequently. When a contactor breaks the current, an electrical arc is established across the contacts and a good amount of heat energy is generated. This increases when the frequency of breaking the current increases and may result in the “welding” or fusing of the contacts and contactor failure.
Fans and Pumps, Drives and Motors
Published in Samuel C. Sugarman, HVAC Fundamentals, 2020
Motor controllers start and stop the motor. HVAC motor controllers are grouped into three categories: manual starters, contactors and magnetic starters. Manual starters are motor-rated switches that have provisions for overload protection. They are generally limited to motors of 10 horsepower or less and are normally located close to the motor. Contactors are electro-mechanical devices that “open” or “close” contacts to control motors and can be remotely and automatically operated. Magnetic starters (aka “mags” or “mag starters”) are contactors with an overload protection relay.
High-Fidelity Modeling and Experiments to Inform Safety Analysis Codes for Heat Pipe Microreactors
Published in Nuclear Technology, 2023
Carolina da Silva Bourdot Dutra, Elia Merzari, John Acierno, Adam Kraus, Annalisa Manera, Victor Petrov, Taehwan Ahn, Pei-Hsun Huang, Dillon Shaver
The tape heater was also operated by the PID controller with a contactor relay based on the temperature. Two-watt transducers (Ohio Semitronics, PC5) were used to measure the power consumed in the heaters. The cooling fluid system was designed as two open loops of air and water for the condenser section, and the mass flow rates were measured by two 3/8-in. Coriolis flowmeters (Endress Hauser, ProMass). The test section was equipped with 39 ungrounded K-type TCs, and 28 small-size, high-accuracy TCs (0.5-mm OD sheathed, Watlow) were used to measure the wall temperature of the heat pipe. The TCs were tied onto the heat pipe surface with 0.5-mm stainless steel wires. The other 11 TCs (1.6-mm OD sheathed) were used to measure the SiC heater outer surface temperatures, the mineral wool pipe insulation surface temperatures, ambient temperature, and the inlet and outlet temperatures of the cooling channels of air and water, respectively. All the data were acquired using a Compact Rio chassis (National InstrumentsTM) and a PC programmed with LabVIEW.
Hybrid power generation forecasting using CNN based BILSTM method for renewable energy systems
Published in Automatika, 2023
T. Anu Shalini, B. Sri Revathi
The solar and wind energy system including battery storage system is built in the laboratory. Figure 25 presents the prototype of the proposed system. The voltage at the PCC is used as a reference voltage by the controller, and the control signal is fed back via inverter and appropriate filters. To operate the inverter with an independent gate driver, the ANN controller needs onboard PWM circuits. Using an EM relay and input–output contact pins, the power contactor is operated. FPGA controller (dsPIC3050) automates the entire system. Figure 26 presents the experimental output waveforms of the PV voltage, current through the inductors voltage across the capacitors , output voltage of the proposed MSZSC, output voltage of the DFIG, rectifier output voltage.
Fabrication and evaluation of tribological properties of Al2O3 coated Ag reinforced copper matrix nanocomposite by mechanical alloying
Published in Journal of Asian Ceramic Societies, 2020
A. Sadoun, A. Ibrahim, A.W. Abdallah
Electrical contact materials are widely used in many applications, such as relay, low voltage circuit breaker, switch and contactor, which are responsible for the conduction of electrical current between stationary and moving parts [1]. The efficiency of electrical contact materials depends on electrical arc, oxidation, cold welding, wear and overheating during the transition and stopping of the current. Therefore, it is desired that the electrical contact materials have a superior oxidation and arc erosion resistance, as well as the outstanding electrical conductivity, thermal conductivity, hardness and chemical stability [2–5].