Pilz PZE 9 safety relay

Pilz PZE 9 Safety Relay Contact Expansion Module: A Complete Guide to Selection, Wiring, and Field Troubleshooting

In the safety control circuit of industrial machinery, it is often necessary to extend safety signals such as emergency stop and protective door switch to multiple actuators or contactors. Although basic safety relays (such as PNOZ X series) or programmable safety systems (such as PNOZmulti) already provide a certain number of safety contacts, the contact capacity or quantity of the original equipment may be insufficient when multiple loads (such as multiple motor contactors, valves, or lights) need to be cut off simultaneously. At this point, a contact extension module is needed that can replicate and add secure output contacts without compromising the original security level.

Pilz's PZE 9 is precisely such a classic contact extension module. It is not an independent safety assessment device, but rather serves as a subordinate extension of the base unit, monitoring the status of its internal relays through the feedback loop of the base unit. This article is based on the PZE 9 operation manual (version 1001635-EN-10), and systematically introduces various power versions, installation and wiring points, coordination methods with different basic units, safety characteristic data, as well as diagnosis and troubleshooting methods for common faults on site (such as contact welding, input circuit disconnection, or grounding faults) of this module. Whether you are renovating an old electrical cabinet or planning a safety circuit in a new project, this article will provide valuable practical references.

Product Overview and Model Selection of PZE 9

2.1 Product positioning and basic functions

PZE 9 belongs to the contact extension module without power outage delay (Add on device without delay on de excitation). Its main function is to:

Receive output signals from basic units such as emergency stop relays and programmable safety systems.

Copy the state of the input circuit to 8 momentary safety normally open contacts (N/O) and 1 auxiliary normally closed contact (N/C).

Monitor the internal relay contacts through feedback loops to ensure the transmission of safety functions.

Key features:

Positive guided relay outputs comply with EN 60947-5-1.

Input circuit support: single channel, dual channel (without cross short circuit detection), or dual channel with cross short circuit detection.

LED status indicators: Power, CH.1 (channel 1 contact closed), CH.2 (channel 2 contact closed).

Wide working voltage range: DC 24V, AC 24V/42V/48V/110-120V/230-240V.

2.2 Model Overview and Selection Suggestions

Order number, power supply voltage type, typical application scenarios

774150 24 V DC with PNOZmulti or PLC safety output coordination

774140 24 V AC traditional AC control cabinet, directly taken from the control transformer

774141 42 V AC AC for specific ships or humid environments (safe extra low voltage)

774142 48 V AC AC control circuit for some old-fashioned machine tools

774143 110-120 V AC North American or specific industry standard voltage

774148 230-240 V AC Common Frequency Voltage in Europe and Asia

Selection guide: Prioritize the 24V DC version (774150), as modern safety systems and PLCs generally output 24V DC, and DC power supply is more stable and responsive. If there is already an AC control power supply on site that cannot be modified, select the corresponding AC version. Note that the maximum allowable total cable resistance in the input circuit for the AC version is different from that for the DC version (see technical parameters for details).

Installation and wiring specifications

3.1 Mechanical Installation

Environmental requirements: The protection level of the control cabinet should be at least IP54. The module itself has a shell protection of IP40 and a wiring terminal protection of IP20.

Installation method: 35mm DIN rail (EN 60715). Use the card slot on the back of the module to insert the guide rail. When installing vertically, fixed clips (such as stoppers or end corners) should be added at the upper and lower ends to prevent vibration slippage.

Heat dissipation and spacing: No special heat dissipation is required, but it should be avoided to closely adhere to high-power heating devices (such as frequency converters and large resistors). The ambient temperature range is -10 ℃ to+55 ℃.

3.2 Core points of electrical wiring

3.2.1 Power Supply

DC version (24V DC): The power supply must comply with SELV/PELV (Safety Extra Low Voltage) standards and have protective electrical isolation. A1 is connected to L+(positive), A2 is connected to L - (negative). Residual ripple is allowed at 160% (i.e. up to a peak of 38.4V).

Communication version (24/42/48/110-120/230-240V AC): A1 is connected to the phase line (L1), A2 is connected to the neutral line (N). The frequency is 50/60Hz and the power consumption is 7VA.

3.2.2 Input circuit (Y1-Y2 terminals)

PZE 9 receives safety output signals from the base unit through terminals Y1 and Y2. According to the type of basic unit and the presence or absence of short-circuit detection, there are three types of wiring methods: