I. Definition of two key breakdown voltages (two items must be read in the manual) 1.Breakdown voltage between disconnected contacts (contact clearance withstand voltage) The maximum voltage that can be withstood between two reeds without arc breakdown when the reed switch is disconnected; How high voltage the contact can switch is determined by the nitrogen/vacuum inside the glass tube and the reed gap. 2.Breakdown voltage of coil ↔ contact quarantine (dielectric withstand voltage of coil contact) The insulation and withstand voltage between the control coil circuit and the high voltage signal circuit is the safety index of the strong and weak current quarantine. The test standard is: AC withstand voltage for 1 minute without breakdown and flashover. II. Conventional standard reed relay (general DIP/SMD, instrument and signal switching) 1.Breakdown voltage between disconnected contacts Common nitrogen-filled reed switch: 250 ~ 600VDC (common 250V/400Vdc) Maximum allowable switching voltage: DC100 ~ 200V, AC100 ~ 265V Note: Breakdown voltage > rated switching voltage. Breakdown is a short-term withstand voltage and cannot work with load for a long time. 2. Coil and contact quarantine withstand voltage (industry general grade) Economical small signal: 500VAC/1min Standard general model: 1000 ~ 1500VAC/1min (the most mainstream, multimeter, acquisition board) III. High-voltage reed relay (insulation test, BMS, semiconductor ATE, medical) Enlarging the gap of the reed, lengthening the glass tube, vacuum packaging, epoxy quarantine, and greatly improving the pressure resistance: Medium and high voltage series (Hongfa HR1-V, Stanmald BH) Breakdown between contacts: 3000 ~ 4500VDC Coil-contact quarantine: 5000-7000VDC Allowable long-term switching voltage: 1000 ~ 1500VDC Ultra-high voltage vacuum reed relay (HVR series, withstand voltage 10 kV ~ 20 kV) Contact gap breakdown: 10000VDC/15000VDC/20000 VDC Coil contact quarantine withstand voltage up to 20 kVdc for withstand voltage tester, PV insulation testing IV. Comparison of Breakdown Voltage of Dry Spring vs Common Electromagnetic Relay Advantages of dry reed relays Glass + nitrogen sealed quarantine, the withstand voltage of quarantine is much higher than that of ordinary electromagnetic relay under the same volume; high-voltage test equipment almost only uses dry spring. Common electromagnetic relay short board The contact is exposed to the air and the internal plastic gap is small. The quarantine withstand voltage of the coil contact is only 500 ~ 1000 VAC at most, and rarely exceeds 1500 V, which is not suitable for high voltage quarantine scenarios. V. Key Points for Attention in Use Breakdown voltage ≠ long-term operating voltage Breakdown is a short-time withstand voltage test value. The actual continuous switching voltage must be lower than rated switching voltage. If it is close to the breakdown value for a long time, micro-discharge will continue and the reed will be carbonized and adhered. Inductive loads generate reverse high voltage spikes that can easily exceed the contact breakdown voltage, and RC absorption/pressure-sensitive protection must be added. High temperature and high humidity will reduce the breakdown voltage, so the high-voltage insulation equipment needs to select the type of extended creepage distance and vacuum dry spring. Type selection distinction: Weak signal: standard 1000VAC quarantine is enough; Battery insulation and withstand voltage test: select the high-voltage type with contact breakdown ≥ 3kVdc and coil quarantine ≥ 5kVac.