Note: Unless otherwise specified below, the description should be based on electromagnetic relays.  

1. Mechanical and Physical Parameter Requirements: Ensure the usage and installation dimensions, weight, sealing, strength, and solderability of the pins, etc. Mechanical parameters include contact pressure, contact gap, contact trace, return spring pressure, armature movement, stopper height, etc.  

2. Electrical Parameter Requirements: Ensure that the relay can operate reliably and correctly under specified usage conditions, accurately reflecting and transmitting speed signals. This includes winding resistance, contact electrical resistance, pick-up current (voltage), rated operating current (voltage), release current (voltage), rated contact load, insulation resistance, dielectric strength, and other electrical parameters.  

3. Time Parameter Requirements: In control circuits, there are usually requirements for the operate and release time of the relay, as well as time parameters for armature switching, contact bounce, pulse distortion, etc.  

4. Environmental Adaptability Requirements: Based on the relay's operating environment, to ensure reliable operation, environmental adaptability items include temperature (extreme high and low temperatures, temperature cycling, thermal shock, low-temperature storage, etc.), humidity resistance (normal temperature with high humidity, high temperature with high humidity), low-pressure resistance, vibration stability and vibration strength, shock stability and shock strength, and constant acceleration. In special environments, there are requirements for salt spray resistance, mold resistance, radiation resistance, transportation, storage, etc.  

5. Life and Failure Rate Index Requirements: Under specified test environmental conditions and contact load, the number of failures of the relay within a specified number of operations must not exceed the product's specified requirements. The failure referred to here means the phenomenon of contact welding during the relay's operation, causing the contact voltage drop to exceed the specified level when the contacts are closed. Relays with reliability index requirements should have failure rate index level requirements.  

6. Safety Specification Requirements: To prevent electric shock and fire, products must comply with relevant national safety regulations, such as China's Great Wall (CCC), the United States' UL, Canada's CSA, Germany's VDE, TUV, etc.  

Not all relays need to meet the above requirements. The technical requirements for relays vary depending on the usage conditions.