Emergency-Stop Devices

Georg Schlegel GmbH & Co. KG is offering a comprehensive range of emergency-stop devices allowing to fulfil the requirements of typical applications of different branches - ranging from the machine building industry, plant engineering up to the lift, vehicle, shipbuilding and crane building industry. Customer can choose from a variety of traditional versions. The illuminated variants offer a plus in safety compared to standard emergency-stops, as they signal the active/inactive status of the emergency-stop by means of a clear colouring. Also here, Schlegel offers different products and has developed an emergency-stop with diagnostic unit which constantly monitors the status of the illumination.

Self-monitoring emergency-stop devices
The production of products and goods is mostly done by complex and extensive production facilities. Nowadays, those facilities are no longer operated as complete systems, they are divided in individual areas. This sectioning has the advantage that the facilities can be adapted to production changes much quicker and that they are more failure-proof in whole. The modular structure offers also other advantages. Among others individual parts can be safeguarded by a separate emergency-stop device. In case of a failure in the production or in case of danger for a person, the relating part of the installation is put into a safe state by operating its individual emergency-stop, the rest of the system keeps on running. When using emergency-stop devices it always has to be considered that the emergency-stop function is a complementary protective measure and may not be used as substitute for other protective measures or safety functions!
An emergency-stop consists – simply described – of a red button, the so-called mushroom head and a contact block which is connected to the electrical control of the installation. In case the mushroom head is actuated in case of a dangerous situation the contact bridge of the contact block is opening. The electrical control identifies the opening as emergency-stop signal and puts the installation into a safe state immediately. If the emergency-stop is operated the mushroom head is latching automatically and can be released by twisting, key release or by pulling, depending on the version. This ensures that the installations stays in a safe state until the damage or danger has been eliminated.
Emergency-stop devices are an important safety aspect for human and machine. Thus, the correct use and functionality should be ensured by different measures.
In order to avoid an inadvertent actuation of an emergency-stop by carelessness, a certain pressure resistance is necessary before being able to operate the head completely and to get it latched. In addition, it is possible to see the status of the emergency-stop by a switching position indicator.
If it is required to improve the switching off of installations and machines by emergency-stops, it is possible to have a redundant system by using a second NC contact. The signal to stop will also be given if one of the both contacts cannot signalise the new status due to an electrical failure (e.g. cable interruption, short-circuit). But the safety measure will fail in case of an improper mounting of the emergency-stop device or in case it has been damaged and the mushroom head is not combined correctly with the contact block. In such cases the operation of the emergency-stop does no longer have any impact to the contact block and is without effect.
To close also this safety gap Schlegel is offering self-monitoring emergency-stop devices. The self-monitoring is provided by an additional NO contact. If the mushroom head is correctly mounted to the contact block, also the connection to the electrical control is given. If this connection between mushroom head and contact block is not available, the emergency-stop behaves like it would have been operated, i.e. it actuates the signal to stop the installation.

Self-monitoring thus means: If the mushroom head and the contact block are not mounted correctly, the system will not run or, in case it is running, it will switch off if the two parts will be separated, e.g. by beating off.

Active/inactive emergency-stop devices
In order to avoid the mixing up of active and inactive emergency-stops it was necessary until recently to lock away or cover the inactive emergency-stop to make it unrecognisable as soon as the relating operating panel or plant part was no longer connected to the overall system. Based on the new EN ISO 13850:2015 emergency-stops now can also indicate the actual operating status by a corresponding illumination. In order to increase the work safety and for a better recognisability of inactive emergency-stops, Schlegel has developed emergency-stops which signal the active and inactive status according to this principle. The mushroom of the new active/inactive emergency-stops is now longer coloured in red, instead it is made in a semi-transparent shade of grey. The transparency allows to illuminate the mushroom in red in case it is in an active status and thus it can clearly be identified as functioning emergency-stop. If the emergency-stop is inactive, the mushroom is not illuminated and grey. An inadvertent actuation of an apparently active emergency-stop in case of an emergency is thus being avoided as it will not be perceived as emergency-stop.
Currently versions with Faston and PCB terminals for mounting diameter Ø 16.2 mm or Ø 22.3 mm are available. On customer request the company also develops individual solutions, e.g. complete systems consisting of operating panel and emergency-stop.

Active/inactive emergency-stops with diagnostic unit
As supplement to the safety function of the Schlegel active/inactive emergency-stops, Schlegel has developed an emergency-stop with diagnostic unit SET_QRBDUV_01, which continuously monitors the status of the illumination. If the illumination fails completely or even if it fails only partially or if the brightness is below a defined value, the emergency-stop signal is immediately and automatically activated. In addition the emergency-stop SET_QRBDUV_01 is designed in a way that a partial operation (only one channel is opening) as well as a cross and earth fault will be recognised via the connection of the evaluation unit.
Beside the red illuminated mushroom the Schlegel emergency-stop QRBDUV also has a yellow illuminated anti-lock collar. In case it is required that an actuated emergency-stop can be better identified, the optional flashing function of the anti-lock collar can be activated if wired accordingly. The degree of protection of the emergency-stop is IP65 and it is available as kit for indoor use or as enclosure version with M12 connection.

Comprehensive range of emergency-stops
The range of emergency-stops of Georg Schlegel GmbH & Co. KG comprises a large number of actuators which are different in size and shape and which are designed for different fields of application. Mounting apertures of Ø 16.2 mm, Ø 22.3 mm and Ø 30.5 mm as well as 23 x 23 mm, 24 x 24 mm and 26 x 26 mm are possible, the degree of protection ranges from IP65 to IP69K, and there are variants with protective shroud or anti-lock collar, key release and emergency-stops for hygienic applications. Nearly all emergency-stops can be realised with release by turning (in either direction) or by pulling. Furthermore the construction of the emergency-stop devices allows the reliable function for voltages up to 440 V and for low voltages which are being required more and more. This is ensured by the self-cleaning function of the contacts and by the springs being dimensioned for a good contact pressure. Customer can either choose silver or gold-plated contacts.
All contact blocks are available for screw connection, with Faston terminals, with Cage-Clamp or push-in connection. They have positive opening contacts acc. to EN 60947-5-1 and there are solutions for one or two channels. Depending on the version a maximum of 4 NC contacts per emergency-stop is possible.