Thermal relays are overload protection devices, mostly for three-phase use. You can use a multimeter resistance range * 100 or * 1K or use a diode range to measure whether the main circuit terminals are in the path. If there is one or more open circuits, it will be bad. Otherwise, it is normal, but also to see whether the normally closed contact is normal, it is closed under normal conditions (it has a manual button, you can press your hand to see if the action is the normally closed contact is opened 7a64e58685e5aeb931333363396436), when the load current When the rated current of the thermal relay is exceeded, it will be automatically disconnected, so that the load contactor coil loses power to disconnect the protective load.
The thermal protector is a thermostat that uses a bimetallic strip as the temperature-sensing element. When the appliance is working normally, the bimetallic strip is in a free state, and the contacts are in a closed / open state. When the temperature rises to the operating temperature value, The bimetallic element generates internal stress and acts quickly when heated, opening / closing the contacts and cutting / closing the circuit, thereby playing a thermal protection role. When the temperature drops to the reset temperature, the contact automatically closes / opens, and the normal working state is restored. Widely used in household appliances motors and electrical equipment, such as washing machine motors, air conditioner fan motors, transformers, ballasts, electric appliances, etc.
Before testing, check the appearance of the thermal relay, whether the thermal components and other parts are good, whether there is corrosion, whether the push reset switch is flexible, normally closed, normally open contact contact status, whether the distance between the three bimetals and the guide plate is the same (cold After confirming that there are no defects, the test can be carried out according to the following procedure: the test environment temperature should be as close as possible to the working environment temperature, and there should be no external airflow influence. 0-10A, connect the three thermal elements in series with the connecting wire, and then use the connecting wire to connect to the test column 3, X2 and X3 terminal short, the thermal relay normally closed point is connected to the self-locking 16 test column, current level Position switch 13 selects the appropriate gear.
The "output selection" switch 26 is moved to the A position, the "voltage regulator" handwheel is close to zero, the "self-locking" switch 11 is disconnected (the handle is down), check that the contact of each terminal post should be good, press "open" The word button 14 turns on the test power supply (when the test power supply cannot be maintained, the "voltage regulator" handwheel can be adjusted slightly larger), and the "voltage regulator" handwheel is adjusted to the rated current of the thermal relay to be tested. The bimetallic plate has reached a thermally stable state (time is not specified), and then check whether the distance between the bending points of the three thermal elements and the guide plate is equal. Hold the root of the bimetallic sheet to make consistent corrections, so as to stabilize the hot state and then adjust the "voltage regulator" handwheel to make the test current reach 1.2 times of the rated current. At the same time, press the "reset zero" button 8 to start timing from zero. Enter the test phase, within 20 minutes, the thermal relay should be tripped as a qualified item, the normally closed contact of the thermal relay connected to the self-locking end column is disconnected, the test current disappears, the timer stops, and the test time is displayed. The light or sound is given, through switch 21, the light or Ring, when the stop signal can click to "Stop" button 22.
Time unit button 5, 0.00S-99.99S; 6,0.0S-999.9S; 7,0S-9999S; 9,0.0min-999.9min. When testing the rated starting current of 6 times, one should start from the cold state of the hot element according to the regulations. For the setting of other parameters of the thermal relay, please refer to the relevant regulations. The ampere-second characteristics of the thermal relay can also be selected according to the load of the protected motor.
