保護 Relay的方法

Relay 的控制線圏開關時會產生火花?
是。當Relay 的控制線圏開關時會產生的,
理解當時的coil接通電流,繼己接通"接點",
該兩點contact point 便會產生火花。
再已理解Relay 的"接點"構造,正如生產商
也知悉該問題,故大多數會採用“白金接點"
來保護因火花產生過熱,接觸不良已引致損毁。


如何保護線圏不受擊毁？
當接線時要清楚該Relay的operating voltage, A/C? DC? 等等
避免因輸入不正確的電壓,繼己引致損毁。

AC和DC控制線圏可否用相同保護方法?
可用相同保護方法。

there is a few methods u can use

put a capacitor in parallel with the coil
it can be use in DC relay. the value of the cap depends on the relay coil. problem of this is it tend to create resonance (it become a RC loop)

install a diode parallel to the coil
can be used in DC relay. the diode to be installed opposite to the supply voltage

install 2 zener diode (diode in serial and opposite polarity) in parallel with the relay coil
can be used in both AC/DC relay. however it is more expensive compare to the 2 other method mentioned above

Relay的控制線圈在通電後, 產生磁場, 將觸點閉合, 形成迴路. 通電時, 只有高低電壓出現時才會有火花的產生, 但線圈實際上並無接觸點, 所以你所說的 " Relay的控制線圈開關時會產生火花 " , 可能是線圈線扎間出現不完全的短路, 產生電壓差而引致打火. 若是這個問題, 就已經不是保護不保護的問題, 而是維修問題.

有火花係冇扮法避免
只有唔好有太大loading