3SE7921-1AA, Siemens Pulley Bracket

3SE7 Emergency Grab Wire Switch

The 3SE7 series of grab wire switches (trip wire switches, cable operated switches) are used for monitoring or for EMERGENCY STOP devices on particularly dangerous system sections.
As the effective range of a grab wire switch is only limited by the length of the grab wire, large systems can also be protected. Switches (requiring pulling at both ends) and conveyor belt unbalance trackers are used primarily for monitoring very long belt systems.

Design

The switches for wire lengths up to 50m are available with 1 NO + 1 NC or 2 NC contacts and for up to 75m with 1 NO + 3 NC contacts. The switches for wire lengths of 2 ´ 75m and the conveyor belt unbalance trackers are supplied with 2 NO + 2 NC contacts.
The grab wire switch and the conveyor belt unbalance tracker are also available with a factory fitted LED (red, 24 V DC). This light has innovative on board chip technology that allows the operating state of the switch to be visible at a distance of at least 50m.

Function

The NC contacts of the grab wire switch and the conveyor belt unbalance tracker are positive opening. The grab wire switches with one side operation are held in free position by the pre-tension on the turnbuckle. In the 3SE7 140 and 3SE7 150 grab wire switches, both switching contacts are available for wire-break/wire-pull signalling. The NO contact can be used, for example, for signalling purposes. On switches with interlocking, with a pre-tensioned wire, the locking must be deactivated beforehand in order to return the grab wire switch to its original position.

Positive latching and positive NC contacts
Switches for wire lengths up to 75m
Metal housing
Enclosure is screw mounted
IP67 rating
Operating temperature: -25 to +70°C

Note

Stock nos. 764-4341, 764-4301, 764-4304, 764-4357 are fitted with an indicator light.

Approvals

UL,CSA

Standards

The switches are equipped with positive latching and positive NC contacts and are therefore suitable for operation in EMERGENCY STOP devices in accordance with EN ISO 13850. They are usable up to Category 4 according to EN 954-1.

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