Mike Dolt Enterprises
Mike Dolt Enterprises
User: MichaelA1965, Location: Everett, WA
Asked on: Saturday, June 4, 2011 at 11:16 pm EDT
Answered on: Tuesday, May 14, 2024 at 6:12 am EDT
Question: Has anyone had any luck with, or is it even legal/code compliant, to install wireless transmitters to operate an E-stop? Specifically, I would be tripping the rectifier circuits that supply my DC bus.I'm working with an industrial (smelter) DC bus system that is 1000 VDC, and 150KA. There is a request by the customer to install wireless E-stops. It is against my better judgement to do something like this, but I must at least explore the options.I'd love to hear your thoughts, but more importantly, I'd love if someone might have experience, or can point me to documents/code sections that will support or not support this method of de-energizing a bus/power.Thanks.
Legality and Code Compliance
The legality and code compliance of installing wireless transmitters to operate E-stops varies depending on the jurisdiction and applicable codes and standards.In the United States, the National Electrical Code (NEC) does not specifically address wireless E-stops. However, it requires all electrical equipment to be listed and installed in accordance with the product's instructions. If wireless transmitters for E-stops are listed by a recognized testing laboratory, their installation may be permissible under the NEC.Other relevant codes and standards include: ANSI B11.19: Industrial Robots and Robot Systems - Safety Requirements IEC 60204-1: Electrical Equipment of Industrial Machines - Part 1: General Requirements ISO 13849-1: Safety of Machinery - Safety-Related Parts of Control Systems - Part 1: General Principles for DesignThese standards may have requirements for the safety and reliability of E-stops, including their wireless functionality.
Wireless E-Stop Systems
Wireless E-stop systems generally consist of a transmitter (worn by the operator) and a receiver (connected to the E-stop circuit). When the operator presses the E-stop button on the transmitter, a wireless signal is sent to the receiver, which triggers the E-stop function.
Considerations
Installing wireless transmitters to operate E-stops raises several considerations: Transmission Reliability
Ensuring the wireless signal is sufficiently strong and reliable to ensure timely E-stop activation in all operating conditions.
Interference and Security
Protecting the system from interference from other wireless devices or intentional attacks that could compromise the E-stop functionality.
Battery Life and Failure
Ensuring that the transmitter batteries have sufficient life and that backups or charging mechanisms are in place to prevent E-stop failure due to battery depletion.
Safety and Liability
Thoroughly assessing the risks associated with using a wireless E-stop system and the potential consequences of a wireless failure.
Other Options
If wireless E-stops are not feasible or do not meet the required safety standards, alternative methods of E-stop activation should be considered, such as: Wired E-stop buttons Pull cords Break-glass E-stops* Remote E-stop pushbuttons connected to a wired circuitRecommendation
Given the high risk and potential consequences of a DC bus E-stop failure, it is strongly recommended to consult with qualified electrical engineers, safety experts, and regulatory authorities to assess the feasibility and safety of installing wireless transmitters to operate E-stops. The decision should be based on a thorough risk evaluation and compliance with all applicable codes and standards. Flag for review