FAQ

Frequently Asked Questions

1.How to Choose the Right Contactor or Relay ?

If your circuit voltage is 12-450V, please check Cost effective DC contactors
If your circuit voltage is 12-900V, please check Epoxy sealed HV DC contactors
If your circuit voltage is 12-1500V, please check Ceramic sealed HV DC contactors

2.How Can I Be Your Distributor ?

We will select one of the most powerful distributor in each area, you will have fully support on delivery time, price and so on, for detailed information, please contact: info@hotsoninternational.com

3.Do You Supply OEM Service ?

Yes, we have a professional engineer team, who can customize for you based on your application request.

4.What Is the Difference Between HOTSON’s ZJQ, EVQ and EVH Series Contactors?

HOTSON provides three different series of contactors ZJQ, EVQ and EVH series contactors. ZJQ and EVQ are Epoxy sealed, whereas, EVH is ceramic sealed. ZJQ is intended to fit in for small low voltage load up to 450V, suitable for forklifts and golf carts. The other two series are high-performance DC contactors, EVQ is suitable for EV charging Station/pile, energy storage and wind power equipment, while EVH is for commercial purposes i.e. military vehicle, heavy truck, electric busses, etc. The current rating is different for all of them. ZJQ has a current rating of 1A-350A, EVQ and EVH has a current rating of 1A-600A and 1A-400A, respectively.

5. What Are the Temperature Requirements for Installing Hermetically Sealed Contactors?

Environmental factors such as temperature and humidity levels also affect the performance of the DC contactors. It is important to take care of these factors when installing your required DC contactors. The ambient temperature suitable for the contactors ranges from -40C to +85C. While the required relative humidity level of DC contactors ranges from 5 to 95% HR level.

6. What Are Desired Preventions to Avoid Failure Modes in DC Contactors?

In order to avoid the problems which can prevent the DC contactors from performing their functions properly, you need to take care of few important factors. The connection while installing the DC contactors should be assembled carefully. The poor connection between the surface stud of the contactor and the copper bar will lead to rising in temperature, which can result in to heating or burning. The equipment should also match the installation requirements for example if the bar and the copper bar are too small to fit in, the gap area between them can also cause temperature rise.

7. What Are the Selection Criteria of A DC Contactor?

While selecting the DC contactors for yourself, there are some criteria based on which it is easier for you to select the appropriate DC contactor. The basic factors you need to keep in mind are; the operational rated current (Ie), operational rated voltage (Ue), the time constant L/R with the utilization category, and lastly the electrical durability of the contactors. Based on these factors you can decide your choice of DC contactor, which will serve your purpose. All the technical aspects of the DC contactors are typically mentioned in the manuals.

8. What Factors Affect the Performance of DC Contactors?

There are two main factors that can affect the performance of the DC contactors, first is the burning of studs. This can be caused by the bad connection between the DC contactor and the external environment, which leads to abnormal temperature rise. Another factor is the contact welding which can be caused because of two main reasons: either the arc is not properly extinguished between the main contacts of contactors, or due to the air leakage between the contacts. You need to avoid these two mistakes to let the DC contactors perform efficiently.

9. What Are the Prevention Techniques to Avoid the Compromise On the Performance Of DC Contactors?

To avoid any discomfort related to your DC contactors working, it is important to take the necessary precautions beforehand during the installation. It is better to opt for a soft row connection between the DC contactor and the external connection. Secondly, The assembly should strictly be performed according to the torsion requirement for each contactor that is mentioned. To prevent the loosening of the nut it is better to add glue to it, to ensure extra safety. The copper bar should also be selected according to the same expansion coefficient as that of a stud, this will keep the nut safe from the back torsion. Lastly, to prevent the contacts from leaking it is preferred to use adhesive filling technology using glue, or another option is to use the Epoxy adhesive formula to keep the contacts intact.

10. What Is the Torsion Requirement of the DC Contactors?

11. What Are the Switching Options in HOTSON’s DC Contactors?

HOTSON provides bidirectional switching, so you have a choice between optional nonpolarized and polarized contacts.

12. What Are the Mounting Requirements for HOTSON’s DC Contactors?

There are no special mounting requirements for our DC contactors because they are not positione sensitive. They can safely be mounted in any direction. But it is better to avoid the environment with mechanical shock or vibration because the average performance of the contactor over time could be influenced by areas of high vibration or high shock.

13. What Is Coil Suppression for DC Contactors?

An unsuppressed coil can create a very high voltage spike or back EMF while a contactor is de-energizing (being turned off), possibly causing damage to the driver or other sensitive circuit. When shutting off a coil, suppressing or clamping the transient voltage is extremely helpful. Therefore, as a consistent procedure for transient clamping, it is recommended to use a Zener-diode. 42 VDC max is a standard relay coil value for back EMF. Also, note that the use of single diode suppression relays with low level to 2A ratings does not affect switching efficiency. Using Zener-diode suppression to prevent the reduction of contact switching for a lifetime and reduce potential contact sticking or welding for relays with 5A and above current rating.

14. What Is the Benefit of Using an Economizer Coil?

An economizer coil usually used in a contactor is a high resistance low current coil. The purpose of the coil is to cut-in hold the contacts closed, after high current transfers the contacts by the pull-in coil, dropping the coil heat and current, while the contactor is still energized. An alternative method of pulse width modulation (PWM) can be used for economizing. The PWM may be used in ground applications and is normally not used in applications with critical flight or high reliability as it may generate EMI problems with sensitive equipment. In this case, the economized coil is a power saver in regards to holding the current.