Vacuum relay is different from other types of relay, its rated current refers to the load current (through), under the rated current, the relay temperature does not exceed the specified value, when the relay is "hot" conversion, with the different circuit load, "conversion current" will probably increase or decrease.
DC Conversion
In vacuum relays, the arc voltage is maintained at about 20V, which is independent of the converted voltage, and has the capability of rapid arc reduction, which makes the vacuum relay have stronger conversion ability than the air relay. For example, JPK-10 has made dozens of transformations at 600V and 100A. However, when the voltage is higher than 1KV, the general conversion current should be limited to no more than 15A, if more current is to be converted. The artificial current zeros can be formed by shunting RC circuits at converting contacts.
AC Conversion
AC current has zero point, and conversion is much easier than DC conversion. However, in application, it is generally smaller than load (through) current. For the same relay, the converted current is larger and the number of electrical life will be reduced. For example, JPK-10 has withstood hundreds of resistive load conversion at power frequency 380V and 300A, and JPK-6 can withstand 10,000 times of power frequency 220V and 50A resistive load conversion.
Capacitive discharge
Vacuum relays are often used to make capacitive circuits short to the ground (leakage) to protect personal safety. At this time, the surge current can be larger than the load current. For example, JPK-3 can discharge surge current through capacitance of hundreds of amperes, along with the discharge pulse energy withstanding 100 joules.
Pulse application
Vacuum relays are particularly suitable for use in radar impulse forming networks. For some artificial lines with duty factor and bandwidth, peak rated voltage and peak current of thousands of amperes can be used.
