Safety Relays

Evaluate a defined safety function reliably

A safety relay takes the signal from an E-STOP, guard switch or protective device, evaluates it to the required integrity, and switches the machine to a safe state. Where the number of functions is bounded and the logic is clear, a relay remains the most direct and maintainable architecture.

E-STOP and guard monitoring Light curtain evaluation Speed and standstill PNOZ family

Discuss Your Safety Application Compare Relay Families

PL eAvailable on selected families

SIL CL 3Available on selected families

22.5 mmNarrow-width devices

Pilz PNOZ safety relay family including PNOZsigma, PNOZcompact and PNOZ X devices

PNOZ safety relaysFamily range shown; select the device from the safety function

PL ePNOZsigma, PNOZcompact

SIL CL 3PNOZsigma, PNOZcompact, PNOZ s30

22.5–90 mmPNOZ X housing widths

Batch size 1myPNOZ build-to-requirement

Relay families

Safety technology selection by application

The families differ in how the logic is created, how many functions one device can carry, and how the architecture is expected to grow. Start from the number of safety functions and the machine type.

Compact

Maximum function, minimum width

PNOZsigma

The manufacturer positions PNOZsigma as delivering maximum functionality in minimum width, with diverse functionality packed into each device.

Applications up to PL e and SIL CL 3, depending on device
Devices are also available for PL c / SIL CL 1 applications
Particularly narrow housing widths for dense panels
Broad function coverage across the family

Best fitMachine builders needing capable functions in constrained panel space.

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Electromechanical

One relay per function

PNOZ X

The long-established electromechanical range, built on voltage-free contacts and two-relay technology, applied as one PNOZ X per safety function.

Voltage-free, electromechanical contacts with 2-relay technology
Housing sizes from 22.5 mm to 90 mm
Contact count varies across the range
Suited to clearly bounded, individually wired functions

Best fitEstablished designs, spares continuity and single well-defined functions.

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Basic functions

Series machinery

PNOZcompact

A deliberately simple device for the recurring basic functions — E-STOP, safety gate, light barrier and light grid monitoring — with fast installation and maintenance.

For applications requiring PL e of EN ISO 13849-1
For applications requiring SIL CL 3 of IEC 62061
22.5 mm wide
Covers the basic safety functions rather than complex logic

Best fitRepeating functions across series-built machines.

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Modular

Built to the requirement

myPNOZ

A modular relay assembled to the specific combination of safety functions required, produced individually in batch size 1 and configured through the myPNOZ Creator.

Produced individually, tailor-made to the stated requirements
Modules from 12.5 mm and 17.5 mm widths
Configured without programming through the myPNOZ Creator
Suits several linked functions that a single relay cannot carry

Best fitSeveral interacting functions, where a configurable controller is not yet warranted.

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Solid state Pilz PNOZelog solid-state safety relay

Electronic logic

PNOZelog

Solid-state safety relays combining electromechanical relay experience with electronics, where wear-free switching and logic linking are the priority.

Reliably monitors up to four safety functions
Wear-resistant electronic switching for long service life
Devices can be linked through logic operations, saving wiring
22.5 mm width

Best fitHigh switching frequency and availability-critical duty; confirm current range.

Motion monitoring

Speed and standstill

PNOZ s30

A stand-alone speed monitor for machines where movement must be monitored rather than simply switched off, using drive feedback.

Safe monitoring of speed, standstill, position and direction of rotation
Speed range monitoring and broken shear pin monitoring on drives
Applications up to PL e and SIL CL 3
Feedback system and drive compatibility must be confirmed

Best fitSafe setup speed, standstill-before-access and run-down monitoring.

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Architecture selection

Match the relay architecture to the machine

The practical decision is how many functions must be evaluated, whether they interact, and whether the machine design is expected to change.

Application	Architecture type	Expansion	Motion capability	Best-fit machine	Main consideration
One E-STOP or one guard	PNOZ X or PNOZcompact	Add a further device per function	Not applicable	Standalone machine or cell	Contact count and reset arrangement
Several functions, tight panel	PNOZsigma	Device-dependent	Separate device required	Series machinery, compact panels	Width against required function
Several interacting functions	myPNOZ	Modular, defined at order	Separate device required	Machines with linked guards and stops	Function combination fixed at build
Frequent switching, long life	PNOZelog	Logic linking between devices	Separate device required	High-cycle production equipment	Confirm current family scope
Movement must be monitored	PNOZ s30	Used alongside the stop function	Speed, standstill, direction, position	Machine tools, converting, handling	Encoder or sensor feedback route
Many functions and diagnostics	Move to PNOZmulti 2	Configurable I/O and expansion	Motion modules available	Complex machines and cells	Relay logic becomes hard to maintain

When a relay is no longer the right answer. Once functions begin to interact, diagnostics are needed, or the design is likely to change, a configurable safety controller usually becomes easier to maintain than an expanding set of wired relays.

Applications

Functions these devices evaluate

The manufacturer lists emergency stop, safety gates, light barriers, light curtains, two-hand controls, speed and standstill among the functions monitored by PNOZ safety relays. Not every device covers every function.

Emergency stop and safety door monitoring in an industrial machine environment

Stop and guard

E-STOP and safety gate

The most common pairing: a monitored stop command and a guard position, evaluated to the required integrity with a defined reset.

Typical routePNOZ X, PNOZcompact or PNOZsigma.

Motion

Speed and standstill

Where access is only safe once movement has stopped or slowed, the machine state itself has to be monitored rather than assumed from a timer.

Typical routePNOZ s30 with a verified feedback system.

Pilz myPNOZ modular safety relay assembled for multiple machine safety functions

Combined functions

Several guards on one machine

When a machine has multiple guards, stops and enabling positions, a modular relay keeps the wiring and the logic in one assembly.

Typical routemyPNOZ configured to the function list.

Before selection or quotation

Engineering prerequisites

A safety relay cannot be selected from a device name alone. These inputs determine the device, the contact configuration and the reset behaviour.

Safety function

Which functions must be evaluated, and how many
Whether the functions interact or are independent
Required performance level or safety integrity level, if determined
Whether movement must be monitored, not only switched off

Input devices

Type of input device and its contact or output arrangement
Single or dual channel, and whether cross-fault detection is required
Whether devices are connected in series, and the effect on fault detection
Cable lengths and the connection method

Outputs and machine response

Contact type, number of contacts and switching load
Stopping element — contactors, drive input, valve or brake
Whether feedback loop monitoring of the contactors is required
Required stop category and expected run-down behaviour

Operation and panel

Manual, monitored or automatic reset, and where the reset is located
Supply voltage and available panel width
Terminal type and whether pluggable terminals are preferred
Diagnostics required by maintenance

Related systems

The relay is the evaluation stage

Detection, evaluation, safe output and machine response form one chain. The relay performs the evaluation; the integrity of the complete function depends on every stage being engineered and validated together.

Guard switches and E-STOP devices

Light curtains and area protection

Contactors with feedback loop

Drive stop inputs and brakes

PNOZmulti 2 as the function count grows

Diagnostics to the standard controller

Safety door and emergency stop devices installed on production machinery

Modernising an existing machine?Retrofit routes across the complete safety portfolio, including what can justifiably remain in place, are set out inMachine Safety Retrofit & Modernisation.