Siemens APT Relays – Principles and characteristics of photorelays
When the input quantity (such as voltage, current, temperature, etc.) reaches the specified value, the controlled output circuit is turned on or off an electrical appliance. It can be divided into two categories: electrical (such as current, voltage, frequency, power, etc.) relays and non-electrical (such as temperature, pressure, speed, etc.) relays. With action ...
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