Safety Brake Switch
The Safety Brake Switch (SBS) is your ultimate solution for ensuring speed and safety when it matters most. Designed to stop vehicles using BLDC motors swiftly and efficiently, the SBS works by shorting the motor phases, bringing the vehicle to a complete halt. Unlike systems that rely solely on triggering Safe Torque Off (STO), which may allow vehicles to coast for several meters, the SBS ensures immediate braking, minimizing risks to both people and infrastructure. The SBS is built with a functionally safe design, fully compliant with ISO 13849-1, Safety Category 3, Performance Level d, providing reliable safety assurance for your critical operations.
How it works
The SBS receives two safety signals from the master safety controller and relays them to the motor drive. Upon command, it ensures the power stage is disabled by accounting for necessary delays, then short-circuits the motor phases to guarantee a rapid and reliable stop. Additionally, it can control the motor's electromechanical brake, engaging it at a defined time after the three-phase short to ensure the motor comes to a complete standstill. The safety master controller can override the electromechanical brake control at any time through the Safety Brake Control inputs.
How the Drive can be Functionally Safe?
During normal operation, the motor is braked by the motor drive according to a defined deceleration profile. However, electronics are susceptible to both software and hardware failures. In critical situations that could pose risks to humans or infrastructure, a certified hardware braking technique is essential. While Safe Torque Off (STO) can be used for this purpose, it leaves the motor in a freewheeling state, which can result in the vehicle taking several meters to come to a complete stop.
Reduced Braking distance
The use of SBS results in a rapid and safe brake compared to systems without it, which rely solely on natural friction. In these systems, the vehicle continues to move under its own momentum, leading to a slower and less predictable stop.
Steps to a Rapid and Safe Stop
Rapid and safe stop with in three steps: Detect the obstacle, trigger the STO and short circuit the motor phases.
Functional Safety matters!
Compliance with ISO 13849-1, Safety Category 3, ensures that our motor will brake reliably, even in the event of a fault. The redundancy of critical components, along with diagnostic and monitoring functions, makes the product functionally safe and ensures operational readiness and reliability.
PWM Braking
To further improve braking torque, SBS employs a patented technique where the 3-phase short is pulsed through the motor phases, rather than applied constantly.
This approach enables the motor to stop even faster than it would with a simple constant 3-phase short, as varying PWM duty cycles produce different levels of braking torque depending on the motor speed.
Product Variants
The product variants are differentiated based on the power connectors, brake supply type; main or auxiliary battery, brake delay, and three-phase shorting PWM duty cycle.
Important Note: Currently, only the vertical Molex variant is available. Please contact us for information on other variants.
For any orders or product-related questions, please contact sales.Roboteq@mail.nidec.com
