PILZ safety relay

Our company has been in the automation industry for 10 years, with our own companies in Germany, the United States, Shanghai, and Guangdong, specializing in the import trade industry.

The PILZ safety relay in Germany is composed of several relays and circuits combined together

A safety relay is composed of several relays and circuits, designed to complement each other's abnormal defects and achieve the complete function of a correct and low misoperation relay. The lower the error and failure values, the higher the safety factor. Therefore, multiple PILZ safety relays need to be designed to protect different levels of machinery, with the main goal of protecting mechanical operators exposed to different levels of danger.

The so-called“PILZ safety relay”It is not "", but rather a regular action taken when a fault occurs. It has a forced guiding contact structure, which can ensure safety in case of contact melting phenomenon. This is different from general relays. As shown in Figure 1.

A safety relay is a necessary control component in a safety circuit, which receives input and outputs deterministic switch signals to the control circuit of the equipment through internal circuit judgment. Simply put, PILZ safety relays are of the dual channel signal type, and can only function properly when both channel signals are normal; During the working process, as long as any channel signal is disconnected, the PILZ safety relay will stop outputting until both channel signals are normal and reset before it can work normally.

When the emergency stop is released, the machine cannot suddenly restart;

In case of a malfunction in the safety circuit of the machine, the power supply of the machine can be stopped;

When the safety circuit malfunctions, the machine cannot be restarted;

Relying solely on dualization is not enough.

Dualization is necessary, but in addition, there are several conditions such as mutual inspection of the dual circuit, confirmation that all safety circuits have been disconnected once, and if necessary, it can be started by the operator. From another perspective, when there is a possibility of grounding caused by a short circuit in the input switch wiring or damage to the wire sheath, it is necessary to prevent sudden machine start-up caused by this.

In fact, for the convenience of constructing safe circuitsPILZ safety relayThe product that combines basic emergency stop circuits and safety circuits into a circuit module with other components is called PILZ safety relay module.

Electromagnetic type

Electromagnetic relays are generally composed of iron core, coil, armature, contact spring, etc. As long as a certain voltage is applied to both ends of the coil, a certain current will flow through the coil, thereby generating electromagnetic effects. The armature will overcome the pulling force of the return spring and be attracted to the iron core under the electromagnetic force, thereby driving the moving contact (normally open contact) and the stationary contact (normally closed contact) of the armature to be attracted. When the coil is powered off, the electromagnetic attraction also disappears, and the armature will return to its original position under the reaction force of the spring, releasing the moving contact and the original static contact. This suction and release achieves the purpose of conduction and disconnection in the circuit. For the "normally open" and "normally closed" contacts of a relay, they can be distinguished as follows: the static contact that is in a disconnected state when the relay coil is not energized is called a "normally open contact"; The static contact in the connected state is called a "normally closed contact" [1]. As shown in Figure 2.

Thermal dry spring

Thermal dry spring relay is a new type of thermal switch that uses thermal sensitive magnetic materials to detect and control temperature. It consists of a temperature sensing magnetic ring, a constant magnetic ring, a reed switch, a heat-conducting mounting plate, a plastic substrate, and other accessories. Thermal dry spring relay does not require coil excitation, but is driven by the magnetic force generated by the constant magnetic ring to operate the switch. Whether the constant magnetic ring can provide magnetic force to the reed switch is determined by the temperature control characteristics of the temperature sensing magnetic ring.

Solid state type

Solid state relay is a four terminal device with two terminals as input and the other two terminals as output, and an isolation device is used in the middle to achieve electrical isolation between input and output.

Taking PNOZ VPILZ safety relay as an example

The key points for using safety relays are as follows: as shown in Figure 3

The connection method of the power supply. In the figure, A1 and A2 are power terminals, with A1 connected to 24V+and A2 connected to 0V.

In the control input circuit, during normal use, it is necessary to connect the required switch conditions between S11 and S12, as well as between S11 and S22. Generally, it is a contact or button contact.

In the reset circuit, corresponding reset conditions need to be connected between S33 and 634. At the same time, the condition between Y1 and Y2 is also part of the reset circuit, and both conditions must be met simultaneously.