![]() Resistance bands – like giant rubber bands – providing resistance when stretched.Weight machines – devices that have adjustable seats with handles attached either to weights or hydraulics.Medicine balls or sand bags – weighted balls or bags.Free weights – classic strength training tools such as dumbbells, barbells and kettlebells.There are many ways you can strengthen your muscles, whether at home or the gym.ĭifferent types of resistance training include: If you vary your resistance training program through the number of repetitions and sets performed, exercises undertaken and weights used, you will maintain any strength gains you make. Variables that can impact on your results include: Vary your progressive resistance training program every six to eight weeks to maintain improvement. Australia’s physical activity and sedentary behaviour guidelines External Link recommend that adults do muscle strengthening activities on at least two days each week. ![]() When you do resistance training repeatedly and consistently, your muscles become stronger.Ī well-rounded fitness program includes strength training to improve joint function, bone density, muscle, tendon and ligament strength, as well as aerobic exercise to improve your heart and lung fitness, flexibility and balance exercises. Resistance training is based on the principle that muscles of the body will work to overcome a resistance force when they are required to do so. Using the test button, it is possible to test the control wiring.Resistance training (also called strength training or weight training) is the use of resistance to muscular contraction to build strength, anaerobic endurance and size of skeletal muscles. NC contacts should be capable of direct switching of contactor coil. NO contact is for trip signaling and NC contact is for disconnecting the contactor. They are provided with two auxiliary contacts – one NO (97-98) and another NC (95-96). If the device is set to auto, a remote reset of OLR is possible. With the manual/auto reset selection button, we can choose between manual and automatic reset of these relays after a trip. ![]() Reset ButtonĪ reset button is present over the overload relay to reset the overload relay after a trip and clearance of fault. In the case of an electronic overload relay, an additional knob for tripping class selection is also provided. The current can be set between the upper and lower limits provided. Using this knob, the rated current of the motor can be set. Ampere range settingĪ rotary knob is present over the overload relay. Supply to the motor can be connected to Terminals T1, T2, and T3. It can be directly mounted to the contactor. Terminals L1, L2, and 元 are input terminals. Parts of a thermal overload relayĪpart from the bimetallic strip and contacts discussed in the working principle section above, there are a few more parts in an overload relay that needs to be understood. They are designed in such a way to withstand the starting current (which is typically 6 to 10 times the full load current) of the motor for a limited period (typically 15-30 seconds depending on the threshold of current). These measurements can be used for more accurate thermal overload protection. In addition, manufacturers offer built-in RTD or thermocouples that can be directly used to measure the winding temperature. Electronic overload relays are much suited for applications that require a frequent start and stop of motors. Some manufacturers build electronic relays with extensive features such as earth fault protection, motor stall protection, etc. Also, Electronic relays are more precise than thermal relays. The major advantage of electronic OLR over thermal OLR is that lack of bimetallic strip results in low heat losses inside the relay. Some electronic overload relays come with current transformers and Hall effect sensors that directly sense the amount of current flow. Temperature is sensed using PTC and the same is used to trip the circuit in case of overload faults. It uses microprocessor-based technology for protection. Instead, it uses temperature sensors or current transformers to sense the amount of current flowing to the motor. Working of electronicĮlectronic overload relays do not have a bimetallic strip inside. ![]() The conductor shall be insulated hence no current flow through the strip. Excessive current flow to the motor heats up the conductor and hence the bimetallic strip. Therefore, it gets heated up directly by the current.īut in the case of indirect heating, the bimetallic strip is held in close contact with the current-carrying conductor inside the OLR. In the direct heating method, the full current to the motor flows through the OLR. As explained above, a bimetallic thermal relay works on the heating property of the bimetallic strip.
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