safety devices (surjeet) (1 and theri use

Device use for safety

1. Introduction of safety devices and their applications Nilesh Sachan

2. Safety is the state of being "safe", the condition of being protected from harm or other danger. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk. SAFETY

3. Common Machine Safety Devices Mechanical hazards on machinery typically occur at points of operation, points of power transmission, and other points of machine movement.  Safeguarding devices are designed to limit the risk to personnel for accident or injury at these points. In the illustration below, common machine safeguarding devices are used to mitigate multiple points of risk on a robotic work station.

4. 1. SAFETY LIGHT CURTAINS Safety light curtains protect personnel from injury and machines from damage  by creating a sensing screen that guards machine access points and perimeters. An individual or object interrupting any beam in the screen will trigger a halt to the hazardous motion.

5. How Do Light Curtains Work? The light curtain consists of two parts: a transmitter and a receiver . - The transmitter  contains multiple LEDs that send pulses of infrared light to the receiver. The pulses emit in sequence, such as from top to bottom, and each pulse releases at a specific frequency. - The receiver  pairs with the transmitter to “expect” these pulses in the right sequence and timing, thereby eliminating (or nearly eliminating) the possibility of interference from other light sources. When an opaque object passes between the transmitter and receiver, that object interrupts the reception of pulses. This interruption triggers the connected device or machinery to stop. Light curtains differ from other  photoelectric sensors  in that they have self-monitoring circuitry. In the event of a fault in their operation, this circuitry sends an automatic stop signal, ensuring that the connected device will not function unless an effective safeguard is present.

6. 2. SAFETY CONTROLLER A  safety controller monitors multiple safety and non-safety input devices , providing safe stop and start functions for machines with hazardous motion. A single safety controller can replace multiple safety relay modules in applications that include E-Stop buttons, safety light curtains, interlocking gate switches, and other safety input devices.

7. 3. TWO-HAND CONTROL DEVICES By requiring that a machine operator use both hands to initiate and continue a machine cycle, two-hand control devices keep the operator at a safe distance from the hazardous motion of the machine. If one or both hands are removed from the device, the machine de-energizes, bringing the hazardous motion to a stop.

8. 4. INDICATOR LIGHTS available in single and multicolor options,  led indicator lights provide high-visibility real-time indication of equipment and safety status . they have a compact, low profile design that enables deployment in areas where other indication solutions would interfere with machine motion.

9. 5 . SAFETY INTERLOCK SWITCHES safety interlock switches monitor the mechanical guards that separate an individual from a hazard . If a guard, like a gate, door, or panel is opened or removed, the safety interlock switches send a signal to the machine control system to halt the hazardous situation.

10. 6 . ENABLING DEVICES Enabling devices initiate a safety function when a user either squeezes or releases the handle grip switch . When continuously activated and used in conjunction with a separate actuating control, these devices allow a machine to function in manual operating mode .  HOW TO CONNECT MODE SELECTOR AND 3-POSITION ENABLING DEVICE Mode selector: The selector can be a key switch with redundant electrical layout or signals from dedicated safety PLC. 3-position enabling device: Requirement to a 3-position Enabling Device is a redundant layout and a push button with three positions, where only the position in the middle creates a connection. Signals must be redundant and connected to two of the configurable inputs in UR control box. Use the 24V terminals on the input connector as indicated on Fig. 

11. 7 . EMERGENCY STOP AND STOP CONTROL Emergency stop devices allow workers to quickly stop a device  by pushing a button or pulling a rope in order to prevent injury to personnel and material loss. These devices are wired to override all other machine controls and remove power from hazardous machine motion.

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