Ningbo Tianbo Ganglian Electronics Co., Ltd.
  • Q: Relay Cleaning


     Dust-proof type, flux tight:

    (1) Hot or soaking cleaning is not allowed.

    (2) Please only brush the soldering surface of the printed board.

    plastic sealed type:

    (1) Hot or soaking cleaning is allowed.

    (2) Please use alcohol or water cleaning solution.

    (3) The cleaning temperature should be controlled below 40 °C.

    (4) Please do not USE ultrasonic cleaning or cut off the terminal of the relay, otherwise the coil will be disconnected and the contacts will be bonded.


    Plastic sealed type relays after being mounted on the PCB and welded may be damaged due to different welding conditions of users. Therefore, if the relay needs to be cleaned after welding, please adopt our recommendation for welding and selecting  a special sealed product. Do not use freon, trichloroethane, thinner diluent or benzine gasoline for cleaning.



  • Q:What is the operating current and rated current of the relay coil?


    Operating current = operating voltage / coil resistance; rated current = rated voltage / coil resistance.

  • Q: What is the significance of applying a rated voltage to the coil during operation? What is the allowable range of fluctuations?


    Applying rated voltage can ensure that the relay can operate reliably when the external conditions ,such as temperature and voltage are changed. The voltage ripple factor should not exceed ± 5%, and the maximum should not exceed ± 10%.

  • Q:What is the significance of the maximum allowable voltage of the coil?


    The maximum voltage that the coil can apply in a short time

  • Q:Will the plastic sealed type relay has higher electrical endurance than non-pleastic sealed type?why?



    1) The electrical life for non-plastic sealed ones will be higher for power relay with large load. Because the arc and heat of the load have great influence on air exchange inside and outside the non-plastic sealed ones,which can take  away part of the heat and harmful gases.But if the environment is dusty and humidity is too high, the plastic sealed is better.


    2)The electrical life for plastic sealed ones will be higher for telecom relay with small load.Because of such a small load,there is almost no arc to have influnence on air circulating. If the internal and external air is connected, more harmful substances will be brought in to affect the contact resistance and lead to failure. Therefore, the electrical life of plastic sealed telecom relay will be higher.

  • Q:What is the minimum applicable load recommended by the power relay?



  • Q:What are the manual welding, wave soldering, and reflow soldering? What is the welding condition?


    Manual welding: Manual use of electric soldering iron for welding, head of eclectric soldering iron temperature: 340 °C -360 °C, welding time: win 3s

    Wave soldering: automatic soldering of electronic components terminal plug-in type, soldering temperature: 250°C-260°C, soldering time: 5s~10s, preheating temperature and time as much as possible within 100°C, less than 1min.

    Reflow soldering: automatic soldering of surface mount relays, soldering peak temperature: 245 °C, soldering time: 220 °C     within 30s, preheating temperature and time as much as possible from 150°C to 180°C,within 1min. You can find more information from the specifications of the relays for reflow soldering.

  • Q:When choosing relay, can the load voltage and current be simply converted by switching power? For example, a relay with a rated load of 10A/250VAC can switch 25A at 100VAC?


    No. Because the current or voltage will affect the switching ability of the contacts, the switching power can not be simply converted.

    For example, the increase of current mainly brings about the effect of overheating, while the increase of voltage mainly brings about the effect of arc intensification.

  • Q: Can the power relay be used for loads below 200mA? why?


    Not sure, it depends on the nature of the load.

    1) Resistive loads and some loads with impulse current less than 200 mA can not use power relays, because the loads are too small to have arc. After the relay is used for a period of time, the contact resistance will become larger, and even the non-conduction will occur. Therefore, power relays cannot be used and telecome relay are required.

    2)Low-power loads such as coils, motors and lamps, although the steady-state current is less than 200 mA, have impulse current or reverse voltage, which can break down the oxide film and keep the contact resistance stable. Therefore, power relay can be used.

  • Q: Common power relay contact gap is about 0.3mm, and it is recommended that the current should not exceed 0.2A when switching current over 60VDC.Why?


    When the voltage breaks through the air and generates an arc, it needs a large current to maintain the arc combustion. Therefore, for contact gap of 0.3mm, the corresponding voltage at the time of the reliable breaking of the DC arc is about 30 VDC.When the voltage is exceeded, the arc can only be pulled out so that the current is small enough to make the arc unable to sustain combustion and extinguish.

  • Q:What are the safety precautions for relays?


    Please note that there is a danger of electric shock if the relay is touched by hand when it is working normally.

    Please be careful to turn off the power before installing, maintaining, and troubleshooting relays including connecting components such as terminals, sockets, etc.

    Please note that when making terminal connections, please check the wiring diagram on the product manual before connecting properly. If the connection is incorrect, it may cause unpredictable malfunction, abnormal heat, fire, etc.

    If contact adhersion, losse contact, wire broken and other undesirable phenomenon occur, it will endanger the property and even life. Please use double safety devices.

  • Q: In order to prevent the insulation degradation of the printed board, what should be paid attention to when surface treatment is required?


    Dust-proof and flux tight relay may cause a malfunction due to the surface treatment agent entering the relay, so do not perform surface treatment or install the relay after surface treatment.

    Since some surface treatment agents have adverse effects on the relay, such as dissolving the cover, please carefully select and confirm the test in actual use.

    Spraying and brushing processes should be used as much as possible in the surface treatment, and the dip coating process is prohibited. The surface treatment agent should be treated with a normal temperature liquid treatment agent as much as possible, and the surface treatment agent should be sprayed when the relay is cooled to normal temperature. The surface treatment agent can be naturally dried; it can also be dried at a constant temperature, but the drying temperature cannot exceed 60℃. At the same time, it is forbidden to lower the drying temperature without drying the surface treatment agent, otherwise it will easily cause the surface treatment agent to be sucked into the interior of the relay and fail.

    When using a special surface treatment process, please contact us to confirm and provide the suitable product.

  • Q:Why is step voltage recommended when applying voltage to the coil of electromagnetic relay?


    If the voltage rises or falls slowly, it will make the contact more jitter and instability when contacts are closed or open. It is easy to lead a sharp decrease of relay electrical life.