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25
2022-01
Main application areas and features of Parokon Technology’s signal isolators
2022-01-25
Answers to Common Questions About Isolators
Applications of PA-Series Signal Isolators in Industrial Environments
Classification of Explosion-Proof Ratings and Introduction to Relevant Parameters
10
Operating principle, wiring diagram, and illustrated instructions for safety relays
Safety Relay: Working Principle, Wiring Diagram, and Usage Instructions – January 13, 2021 A "safety relay" is composed of multiple relays and circuits working together to compensate for each other's potential defects, ensuring reliable operation with minimal false activations. This design reduces the likelihood of errors and failures, thereby enhancing safety. It is important to note that a safety relay is not a "fault-free relay"; rather, it performs predetermined actions when a fault occurs. Featuring a forced‑guide contact structure, it ensures safety even if contacts become welded shut—something typical relays cannot guarantee. Parokon safety relays are an essential control component in safety circuits. They receive safety inputs, process them internally, and then output deterministic switching signals to the equipment’s control circuitry. Simply put, safety relays operate on a dual-channel principle: they only function properly when both channels deliver normal signals. If either channel fails, the relay immediately ceases output until both channels return to normal and reset. Working Principle of Parokon Safety Relays 1. Electromagnetic Type An electromagnetic relay typically consists of an iron core, coil, armature, contact springs, and other components. When a voltage is applied across the coil terminals, current flows through the coil, generating an electromagnetic field. Under this magnetic force, the armature overcomes the spring tension and moves toward the core, closing the normally open (NO) contact and opening the normally closed (NC) contact. Once power to the coil is removed, the electromagnetic attraction vanishes, and the spring returns the armature to its original position, disconnecting the contacts. Through repeated cycles of attraction and release, the relay achieves on/off switching within the circuit. The distinction between NO and NC contacts is as follows: the stationary contact that remains open when the coil is de-energized is called the NO contact, while the stationary contact that remains closed when energized is called the NC contact. 2. Thermal‑Sensitive Dry Reed Relay A thermal‑sensitive dry reed relay is a novel type of temperature‑sensing switch that uses thermally sensitive magnetic materials to detect and regulate temperature. It comprises a temperature‑sensitive magnetic ring, a permanent magnetic ring, a dry reed switch, a heat-conducting mounting plate, a plastic substrate, and several auxiliary components. Unlike conventional relays that rely on coil excitation, this device operates via magnetic forces generated by the permanent magnetic ring. Whether the permanent magnet can exert sufficient force on the reed switch depends on the temperature‑control characteristics of the temperature‑sensitive magnetic ring. 3. Solid-State Type A solid-state relay is a four-terminal device with two terminals serving as inputs and the other two as outputs. An isolation element separates the input and output circuits electrically. Wiring Diagram for Safety Relays Internal Circuitry of Parokon Safety Relays: Two application-specific wiring diagrams for Parokon safety relays are shown below: Usage Instructions for Parokon Safety Relays In everyday operations, such relays are commonly found in electrical control systems, particularly in imported foreign equipment. Especially during sudden equipment malfunctions, the system must remain inactive until the fault is resolved or confirmed. This precaution prevents hazardous situations arising from unexpected equipment startup after a failure. Consider a specific safety relay model; its internal control circuitry is illustrated below: Key Points for Using Parokon Safety Relays: 1. Power Connection: In the diagram, A1 and A2 represent the power terminals, with A1 connected to +24V and A2 connected to 0V. 2. Control Input Circuit: During normal operation, appropriate switching conditions must be connected between S11 and S12, as well as between S11 and S22. These are typically contact switches or push-button contacts. 3. Reset Circuit: Between S33 and S34, corresponding reset conditions must be established. Simultaneously, the conditions between Y1 and Y2 also form part of the reset circuit; both sets of conditions must be satisfied concurrently. How Do They Operate? A. For the safety relay to engage (i.e., K1, K2, K4, and K5 become energized), simply having power at the input terminals (S12 and S22) is insufficient. To ensure all these contacts close, in addition to power at S12 and S22, the condition requiring K3 to be energized must also be met. B. If K3 is energized, the prerequisite is that K1, K2, K4, and K5 are all de-energized, while the reset circuit must also be powered (i.e., terminal Y2 must have power). Specifically, this means S33 and S34 must be conducting, and both Y1 and Y2 must simultaneously be energized. Example: Consider the control circuitry of a certain piece of equipment, which includes the following configuration: According to the wiring diagram above, if the external emergency stop button is pressed, K11 will lose power. Even after resetting the external emergency stop switch—meaning the input circuit already has power—the internal relay K11 will only regain power once the fault confirmation button on control box 190SP1 is pressed. In summary, upon releasing an emergency stop, the machine must not restart unexpectedly. Instead, the operator must first confirm the fault by pressing the designated fault‑confirmation button before power can be restored, thus ensuring personal safety and protecting the equipment. Parokon Safety Relay Models The Parokon PASR series safety modules primarily serve as protective components between safety devices (such as safety door switches, emergency stop buttons, and light curtains) and start/stop control elements (including relays and hydraulic solenoid valves). Their role is to verify critical safety inputs—for example, whether a safety door is fully closed, whether a light curtain is obstructed, or whether a safety valve spool is jammed. PASR‑9000A: Suitable for monitoring emergency stop switches and safety doors. PASR‑9000B: Suitable for monitoring safety mats or edge sensors. PASR‑9000N: Suitable for monitoring NPN-type light curtains. PASR‑9000P: Suitable for monitoring PNP-type light curtains. PASR‑9000S: Suitable for two‑hand start controls. PASR‑9002T: Suitable for monitoring emergency stop switches and safety doors.
2022-01-10
31
2014-10
Six Key Aspects to Know for the Safe Use of Safety Barriers
The safety barrier isolates and converts voltage and current signals from the hazardous area into either a single‑channel or two mutually independent current/voltage signals for transmission to the safe area. It also supports serial communication networking in the safe area via a configurable communication interface. As an intelligent safety barrier, this product allows users to configure the input signal type and output range using a dedicated programmer or a computer.
2014-10-31