We all know that there are many different kinds of relays according to different classifications, and each has its own role. The commonly used relays are electromagnetic relays, magnetically maintained wet reed relays, solid state relays, etc. The electromagnetic relays can be divided into AC electromagnetic relays, DC electromagnetic relays, high current electromagnetic relays, small electromagnetic relays, bistable relays, counter-current relays and many others. There are also many kinds of automotive relays, generally for small lights, near light, far light, horn, start, preheat, signal, wipers, air conditioning, lift, brake lights, etc.
Relays, basically the parts that use electricity basically have relays. So here's the difference between signal relays and power relays?

Signal relays are generally used to monitor and protect the secondary protection circuit in the distribution of high-voltage cabinets are more often used. For example, if the transformer oil temperature exceeds 85 degrees, the temperature monitoring indicator has a normally open contact 9 closed, the contact string in the signal relay coil circuit, so there is a signal will lead to the signal relay coil 9 suction, the signal relay action, "light" off the sign, while the high voltage switch off, unloading the transformer, thus protecting the transformer. However, the signal relay 9 is also divided into many kinds, some of them are directly beeping or flashing as an alarm signal.

When the secondary protection circuit operates, the signal relay is activated. It will tell the person concerned exactly which protection has gone wrong, and its appearance has a clear sign of activation.
A power relay is a type of relay that generates a jump in one or more electrical output circuits when the input (or excitation) meets certain specified conditions.

The power relay is a device that produces a jump in one or more electrical output circuits when the input (or excitation) meets certain specified conditions. It can be used in the neutral point direct grounding system Q, as the directional component of the zero sequence current protection .

The above is all about the difference between power relays and signal relays, but you should also check the data sheet carefully when selecting the type. Each relay has its own index, according to the design circuit needs to select the relay.