Contactor as a low voltage switchgear in the automatic control of low voltage electrical appliances, after put into use to carry out appropriate maintenance.
The service life and reliability of contactor depend not only on the technical performance of the product itself, but also on whether the product is properly used and maintained.The contactor in the low-voltage switch cabinet should pay attention to the following aspects in use:
1. The rated voltage of the contactor shall be greater than or equal to the rated voltage of the load circuit.The rated current of the main contact is greater than or equal to the rated current of the load.The rated current of the main contact should be selected to be higher in the case of frequent starting, braking and positive and negative rotation.
2. The coil voltage can be lower from the perspective of personal and equipment safety;But from simplify control line, save transformer consideration, also can choose 380V.The coil voltage shall be consistent with the control circuit voltage, and the number and type of contacts of the contactor shall meet the requirements of the control circuit.
3. Ac or dc contactor shall be selected according to the current type of the controlled object.If the control system is mainly ac objects, and dc object capacity is small, can also use ac contactor, but the contact rated current to choose larger, 20A above the contactor with an arc mask, using the electromagnetic force generated when the circuit is disconnected, fast break the arc, in order to protect the contact.
4. Before installing the contactor in the switch cabinet, please check whether the data on the nameplate and coil (such as rated voltage, current, operating frequency and load factor, etc.) of the product conforms to the actual use requirements.Attention should be paid to the moving part of the splitter contactor during installation. The product should be flexible and free from sticking.When the core surface of the contactor is coated with anti-rust oil, the switch cabinet contactor should wipe the anti-rust oil on the core surface before putting into use, so as not to cause the power failure of the contactor.Check and adjust the working parameters of the contacts (opening distance, overshoot, initial pressure and final pressure, etc.), and make all the contacts contact at the same time.
5. When the contactor is installed in the switch cabinet, it shall pay attention not to leave out the screws, washers and wiring head parts, so as not to fall into the contactor and cause stuck or short circuit phenomenon.The screws should be tightened to prevent vibration during installation.After installation, check whether the wiring is correct. Under the condition that the main contact is not charged, first energize the suction coil for several times to check whether the product is reliable before putting it into use.For the contactor used for reversible conversion, in order to ensure the reliability of the interlock, in addition to the electrical interlock, should also add binding mechanical interlock mechanism.
6. When using the contactor in the switch cabinet, please check each part of the product regularly, the movable part is required to be free from sticking and the fastener is not loose, and the parts should be replaced in time if they are damaged.Contact surface should always be clean, do not allow oil;When the contact surface is formed by the action of the arc metal beads, should be promptly cleared.When the contact is seriously worn, the contact should be replaced in time.However, it should be noted that the contact resistance of black oxide film generated on the contact surface of silver and silver-based alloy when the arc is broken is very low, which will not cause bad contact phenomenon. Therefore, it is unnecessary to file and repair, otherwise the contact life will be greatly shortened.The original contactor with an arc extinguishing chamber must not be used without an arc extinguishing chamber to avoid short-circuit accidents.The ceramic arc extinguishing cover is fragile. Avoid collision. If broken, replace it in time.
The above six points are about the installation of contactor, wiring in the low-voltage switchgear, and the precautions for use after installation.We need to pay special attention, otherwise it will affect the service life and reliability of the contactor.