SICK Safety Switches NZ | RE13 RE27 STR1 RFID TR10 i110 Locks

SICK Safety Switches and Interlocks

SICK / Safety switches and interlocks

Wiring contact-based safety switches in series can hide faults. It is called fault masking, the circuit still appears healthy, and it is the reason a guard chain may not deliver the level it was designed for.

SICK safety switches guard doors, hatches and gates across New Zealand plant. RE magnetic, STR1 RFID, and the i and TR locking devices.

Fault masking, and how to avoid it

The most important thing on this page, because it affects installations that look correct.

When contact-based safety switches are wired in series, a fault in one switch can be hidden by the others. The chain still opens when a guard opens, so nothing looks wrong, and the fault detection the safety level depended on is no longer there.

Approach	Fault masking risk
Contact switches wired in plain series	Yes
Series with Flexi Loop and a Flexi Soft controller	Prevented. Each sensor individually monitored
RFID switches with OSSD outputs, such as STR1	Prevented

Flexi Loop allows series connection while individually monitoring each sensor, which SICK states permits performance level e with no compromise in safety.

So if a machine has six guard switches daisy-chained into one input, that is worth raising. The fix is Flexi Loop or OSSD switches rather than more inputs.

See our Flexi Soft page for the controller side.

An RE switch is not PL e on its own

The second conditional rating worth understanding.

SICK states the RE magnetic switches reach up to performance level e, as long as you are using safety controls that have test pulses.

The test pulses connect to the potential-free contacts of the switch to reliably detect short circuits. Without them, the short circuit is undetected and the achieved level drops.

Evaluation unit	Provides test pulses
Flexi Soft	Yes
ReLy safety relays	Yes
A plain relay or standard input	No

So the rating belongs to the combination, not the switch. Same principle as the Schneider Preventa modules on our Preventa page.

If someone specifies a PL e switch and wires it to a standard input, the paperwork and the installation disagree.

The RE magnetic switches

The RE1 and RE2 families cover RE11, RE13, RE15, RE21, RE23 and RE27.

Item	Specification
Principle	Magnetically operated, non-contact, with coded magnetic actuators
Response range	Up to 7 mm on the RE13, up to 9 mm across the range
Contacts	2 or 3
Rating	Up to PL e to EN ISO 13849, with a suitable evaluation unit
Connection	Plug connector or connected cable
Flexi Loop	M12 plug compatible on some variants
LED	On the RE27

Complementary and equivalent contacts are different

A distinction that decides compatibility.

Contact arrangement	Switches
Equivalent, two normally open	RE13, RE23, RE27
Complementary, one NC and one NO	Other RE variants

SICK notes that certain accessories can only be combined with magnetic safety switches having equivalent contacts, namely the RE13, RE23 and RE27.

So substituting a complementary switch for an equivalent one changes the circuit behaviour and may not work with what it connects to. Check the contact arrangement, not just the response range.

Why magnetic switches suit washdown

SICK positions them for areas where a high level of contamination occurs.

Advantage
Simple to clean, enabling high hygiene standards
Greater tolerances, so they suit guards that are hard to guide precisely
No contact with the actuator, so little wear
Low maintenance

Tolerance to door misalignment is the practical reason these get fitted. A sagging door that trips a mechanical interlock will often keep working with a magnetic switch.

SICK publishes horizontal installation tolerance up to 30 mm on some non-contact devices.

So if a guard is nuisance-tripping because the door has dropped, a non-contact switch is the fix. Adjusting the door is better, and not always possible.

STR1, the RFID switch

Where manipulation protection matters.

Item	Specification
Response range	Up to 14 mm
Outputs	2 OSSD safety outputs
Rating	PL e and SIL 3
Active surfaces	Three, so activation from three sides
Actuators	Four different sizes
Series connection	Up to 30 sensors
Diagnostics	Intuitive diagnostic function

Three coding levels, and one of them is a teach-in

This decides whether a replacement is plug-and-play or needs commissioning.

Coding	Behaviour
Universally coded	Accepts all actuators
Uniquely coded	An actuator must be taught in. Only that actuator is then accepted
Permanently coded	An actuator must be taught in. Permanent

Higher coding is what prevents defeating a guard with a spare actuator taped to the frame. That is the whole point of the feature, and EN ISO 14119 requires it where defeat is foreseeable.

Practical consequences:

A universally coded replacement works immediately. A uniquely coded one needs the actuator teaching in.

And a permanently coded switch cannot be re-taught. If the actuator is lost or damaged, you need a new switch as well.

Tell us which coding your installation uses.

Series connection adds response time

A specific and easily missed figure. SICK states that in a safe series connection, each downstream safety switch increases the system response time, and that 0.1 seconds must be added for each sensor to the start-up time.

With 30 sensors in series that is 3 seconds.

That is not a fault, and it is worth knowing before someone chases a machine that seems slow to become ready. It also means a long chain has a longer stop response than a single switch, which feeds into the safety distance calculation.

Locking devices

Where a guard must stay shut until the machine is safe.

Device	Type	Locking force
TR10 Lock	RFID interlock, PL e	Up to 3150 N
i14 Lock	Electro-mechanical, power to lock or release	Up to 1000 N
i110 series	Electro-mechanical	770 N
RFID locking, electromagnet	PL e and SIL 3	500 N

Power to release and power to lock

The principle that decides what happens in a power cut, and they are opposite.

Principle	On loss of power	Suits
Power to release	Stays locked. Power is needed to unlock	High inertia machinery that keeps running after a stop
Power to lock	Unlocks. Power is needed to hold it shut	Where trapping a person inside is the greater risk

These are not interchangeable and the choice is a risk assessment decision. A power-to-release device on a machine where someone could be shut in, or a power-to-lock device on a flywheel that coasts for a minute, are both wrong in serious ways.

Check the existing device before ordering. It is the single most important characteristic of a locking device and it is not always obvious from the outside.

Locking force is a real number

From 500 N to 3150 N across the range.

The force has to hold against a determined person. If a guard is being forced and the interlock is failing mechanically, the answer is a higher locking force, not another identical device.

The electro-mechanical switches

Item	Specification
Family	i12S, i16S, i17S, i110S and related
Use	Safe and economical door monitoring with retaining force
Switching	Slow-action switching elements
Housing	Plastic or metal
Enclosure	IP67
Type	Type 2 electro-mechanical to EN ISO 14119
Coding level	Low to EN ISO 14119

Low coding level matters. EN ISO 14119 treats a low-coded actuator as easier to defeat, which affects what additional measures the assessment requires.

If manipulation is a realistic concern, that is the argument for an RFID switch rather than a mechanical one.

EN ISO 14119

The standard SICK references throughout, covering the design and selection of interlocking devices.

Its central concern is preventing the manipulation and bypassing of protective devices, which is why coding level appears on every SICK safety switch datasheet.

Coding level	Typical device
Low	Electro-mechanical switches with separate actuator
Low or high	Magnetic and RFID switches, depending on coding
High	Uniquely and permanently coded RFID

The other families

Family	Notes
TR4 Direct	Rugged safety switch, IP69K, for harsh environments
TR10 Lock	RFID interlock with guard locking
i10, i14, i15, i110	Electro-mechanical switches and locking devices
Inductive position monitoring	Metal actuation, 4 to 15 mm response, 2 OSSD outputs, PL d

IP69K is the washdown rating, covering high pressure and high temperature cleaning. In a New Zealand meat plant that is the specification that survives.

Note the inductive position monitoring devices are PL d, not PL e. They monitor safe position rather than guard closure, and the rating reflects that.

Actuators are separate parts

The same trap as every non-contact safety device.

The switch and the actuator are separately ordered. On the STR1 the actuator comes in four different sizes, and on the RE range the actuators are coded magnets.

So if a door has been rehung and only one half is damaged, that is a single part order. Tell us which.

And on a uniquely coded RFID switch, a new actuator has to be taught in. On a permanently coded one it cannot be.

What to send us

The full type code and the 7-digit order number.

Switch, actuator, or both.

The coding level, if it is an RFID switch.

Power to release or power to lock, if it is a locking device.

Contact arrangement, equivalent or complementary, on an RE switch.

What it connects to. Flexi Soft, a safety relay, or a series chain.

Important: safety replacements

Safety switches form part of a machine's certified safety function, and the achieved level depends on the evaluation unit as much as the switch.

A like-for-like replacement preserves the assessment. A substitution may not, particularly across contact arrangements, coding levels or locking principles.

We will supply exactly what you specify. If you ask for an alternative we will say what we believe is equivalent and what differs, but the decision belongs with whoever is responsible for the machine's safety. We are a parts supplier, not your safety engineer.

What we can supply

Current production. RE1 and RE2 magnetic switches, STR1 RFID switches, TR4 and TR10, the i series electro-mechanical switches and locking devices, actuators in all sizes, Flexi Loop hardware and cordsets. Quoted with a delivered lead time.

Actuators separately. Usually the cheaper repair.

Discontinued. Earlier SICK safety switches. Surplus and tested used.

We buy SICK safety switches

Safety switches hold value, and a matched switch and actuator pair is worth more than either alone. Keep them together. See Sell To Us.

Send us your part numbers

Tell us whether you need the switch, the actuator or both. And if guard switches are daisy-chained into one input, ask us about Flexi Loop. Quotes in NZD including GST.

Request a quote

Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with SICK AG. SICK, Flexi Loop, Flexi Soft and ReLy are trademarks of SICK AG. All trademarks, brand names and part numbers are the property of their respective owners and are used here for identification purposes only. Information on this page is for identification and does not constitute a safety assessment.