Shanghai Chenzhu Instrument CO., LTD.
Shanghai Chenzhu Instrument CO., LTD.

The Role of Safety Relay Contacts

Feb 09 , 2023

The "safety relay" is not a "no-fault relay", but a regular action in the event of a fault. It has a forced guide contact structure to ensure safety in case of a fused contact, which is completely different from the general relay.

Contact is an important part of the safety relay, but in the process of use, its performance will be affected by different factors, such as contact material, type of load, operating frequency, atmospheric conditions, contact configuration, etc. Next, Shanghai Chenzhu Instrument CO., LTD. will take you to understand the role of relay contacts.

1. Contact protection circuit of safety relay

A contact protection circuit designed to extend the expected service life of the relay is recommended. This protection has the added benefit of suppressing noise and preventing the generation of carbide and nitric acid, which would otherwise be generated on the contact surface when the relay contacts are opened. However, without proper design, the protection circuit may have some adverse effects, such as prolonging the release time of the relay.

2. Contact current of safety relay contact

The current flow through the contacts directly affects the performance of the contacts. For example, when safety relays are used to control inductive loads, such as motors or lamps, the contacts will wear out faster and, due to the increased inrush current of the contacts, metal deposits will often be generated between the mating contacts. Therefore, in some parts, the contacts will not open.

3. Contact voltage of safety relay contact

When the relay is disconnected, the inductive loads can generate a fairly high counter-electromotive force in the contact circuit of a relay. The higher the counter-electromotive force, the greater the damage to the contacts. This can cause a serious reduction in the switching capacity of the DC changeover relay. This is because unlike AC changeover relays, DC changeover relays do not have a zero crossing point. Once the arc is generated, it is not easy to reduce it, thus extending the arcing time. In addition, the unidirectional flow of current in the DC circuit can cause the contacts to build up and wear out quickly.

A safety relay is a relay that makes a regular action in case of a safety accident and has a high factor in safety. It is a combination of a relay and an electric circuit, which has a forced guide contact structure. The safety relay is different from the pressure relay in that it is mainly designed to protect the operator of machinery in different hazards. Since the birth of safety relays, it has greatly reduced the occurrence of safety accidents and thus safeguarded the lives of machine operators. The above is the role of the safety relay contact introduction. We hope it will help you.