EUCHNER TZ1RE024SR11 Guard Locking Safety Switch, 24 V

A proven metal guard-locking switch for hinged guards

The TZ1RE024SR11 (order number 070826) is a TZ-family safety switch that holds a guard closed by spring force and releases it only when its solenoid is powered. That closed-circuit current principle means the guard stays locked after a power failure, which is what you want where run-down time is long, for example on mixers, saws, presses and conveyor enclosures. The actuating head is fitted on the right and the unit connects through an SR11 plug connector (11-pin plus PE), so the switch can be swapped without rewiring.

Two contact blocks report the state of the guard: the door-monitoring block (SK 528) and the guard-lock block (UK 528) each provide one positively driven contact and one NO contact. Two freely assignable LEDs, red and green, show the status on the housing. A front auxiliary release lets a trained person open the guard after a malfunction; EUCHNER notes that it must be protected against misuse by sealing or lacquer.

Technical specifications

Choosing the actuator and the contact scheme

The actuator is not included and has to be ordered separately. EUCHNER lists the straight steel actuator Z-G (016849), a stainless version Z-GME made of solid stainless steel, and radius actuators for hinged doors among the accessories. The overtravel you can tolerate depends on the actuator: 4 mm with Z-G and 16 mm with Z-GN, which is useful when the guard sags or has play.

The data sheet quotes B10D values of 3 x 10^6 for both monitoring functions with a 20-year mission time at DC-13, 100 mA and 24 V. The performance level you reach depends on how the switch is wired and evaluated, not on the switch alone, so calculate it for the complete safety function. Related reading: the transponder-coded EUCHNER CTP guard locking switch shows the electronic alternative to this mechanical design.

Mounting the TZ switch and actuator on a hinged guard

Fit the TZ1RE024SR11 to a rigid part of the machine frame, not to the moving guard, and mount the separately ordered actuator on the door so that it enters the head squarely when the guard closes. Use the fixing holes and screws described in the EUCHNER operating instructions, and secure the actuator with fasteners that cannot easily be removed, so that it cannot be unscrewed and used to defeat the switch. A door stop is needed: the switch head must never act as the mechanical end stop for a slamming guard, because repeated impacts shorten the life of the head and the actuator.

Check the alignment with the guard closed and opened several times by hand before connecting power. The actuator should slide in without scraping the head opening, and the guard should not be able to move so far that the overtravel limit for the chosen actuator is exceeded. On heavy hinged doors that sag with age, recheck this alignment periodically.

Wiring and commissioning the guard-locking function

Wire the SR11 plug connector according to the terminal assignment for the contact blocks, and bring the positively driven contacts of both the door-monitoring and the guard-lock blocks to a suitable safety relay or safety controller. Commission the function step by step: with the guard open, the machine must not start; with the guard closed but the solenoid powered, the guard must open freely; with the solenoid de-energised, the guard must stay locked and the lock-monitoring contact must confirm it. Test the release logic against the real run-down time of the machine so that the solenoid is only powered once hazardous motion has stopped. Seal the auxiliary release after testing, as EUCHNER requires.

Using the switch in Oman and GCC workshops

Production halls in Oman and other Gulf countries can be hot, and enclosures, saws and mixers often stand close to heat-producing equipment. The data sheet reduces the fuse and current ratings at higher ambient temperatures, so check the real temperature next to the switch and size the fuse to the lower value where that applies. Fine dust, wood chips or product residue can collect inside the head opening; keep it clean and inspect it during planned stops. In wash-down or humid coastal areas, make sure the plug connector is fully seated and that its seal is intact, since the housing protection depends on a correctly mated connector.

Maintenance and inspection routine

Include the switch in the regular safety inspection of the machine. Check that the actuator and switch fixings are tight, that the actuator shows no deformation or heavy wear, and that the LEDs report the expected state as the guard is opened, closed and locked. Try to open the locked guard by hand to confirm that it holds. Replace a damaged actuator rather than bending it back into shape, and document every test so that the history of the safety function is available to inspectors.

Documents and quotation

The EUCHNER operating instructions for the TZ safety switch (document 2088062, English) are attached to this page. Please confirm the contact scheme, voltage, plug connector, head position and required actuator before ordering. Seven Star LLC is an independent supplier in Muscat and quotes the exact order code you send.

More products in this range: Safety Switches & Guard Locking.