Pilz PNOZ XV3P safety relay

Pilz PNOZ XV3P safety relay: complete manual for selection, delay configuration, and on-site troubleshooting

In the safety control of industrial machinery, equipment such as emergency stop buttons, protective door switches, and gratings need to reliably cut off hazardous sources. However, many applications not only require immediate disconnection of the main circuit, but also require cutting off auxiliary actuators (such as brakes, pressure relief valves, or auxiliary contactors) after a specific delay. Pilz's PNOZ XV3P safety relay is designed for such scenarios: it integrates 3 instantaneous safety normally open contacts and 2 delayed disconnection safety normally open contacts, while supporting single/dual channel input, automatic/monitored start, and cross short circuit detection. This article is based on the PNOZ XV3P operation manual (version 20122-EN-09), which systematically introduces the selection points, wiring specifications, delay setting methods, safety characteristic data, and the most commonly encountered fault diagnosis and troubleshooting processes on site for multiple models in this series. Whether you are integrating this relay for the first time or troubleshooting an unknown fault on an old production line, this article will provide hands-on technical guidance.

Product Overview and Model Selection

2.1 Core Functions

PNOZ XV3P is a safety relay with delayed disconnection function, which complies with EN 60947-5-1 and EN 60204-1. Its typical applications include:

Emergency stop monitoring (E-STOP)

Safety door switch (with or without cross short circuit detection)

Grating/safety switch

Key output configuration:

Instantaneous safety contacts: 3 normally open (13-14, 23-24, 33-34), open immediately after the input circuit is disconnected.

Delay safety contact: Two normally open channels (47-48, 57-58) will only open after the set delay time (tv) has ended.

No auxiliary contact (N/C) output.

Operation mode:

Single channel (no redundancy, but can detect ground faults)

Dual channel with cross short circuit detection (highest safety level)

Dual channel without cross short circuit detection

Startup method:

Auto start (activated when input circuit is closed)

Monitored startup (requires additional closure of the startup circuit, such as pressing the reset button)

2.2 Model Overview and Selection Suggestions

PNOZ XV3P offers multiple delay ranges, fixed or adjustable delays, as well as screw terminal or spring terminal versions. The main order numbers are as follows:

Order number Power delay type Terminal type Delay range Typical application scenarios

777514 24V DC fixing screw, 0.5 second rapid braking control

777512 24V DC adjustable (knob) screw 0~3 s (12 gears) universal short delay

777510 24V DC adjustable (knob) screw with 0~30 s (12 gears) delayed exhaust or pressure relief

777517 24V DC fixing screw with 10 seconds medium delay

777518 24V DC adjustable (knob) screw 0~300 s (12 gears) long delay cooling or shutdown process

787512 24V DC adjustable (knob) spring loading 0~3 s anti vibration occasions

787510 24V DC adjustable (knob) spring loading 0~30 s anti vibration delay

787518 24V DC adjustable (knob) spring loading 0~300 s anti vibration long delay

Selection criteria:

Delay accuracy: The adjustable version has a delay accuracy of -15%/+15%+50ms and a repetition accuracy of 2%. For situations with strict time requirements (such as robot collaborative stopping), it is recommended to prioritize the adjustable version and conduct actual testing and verification.

Terminal type: In high vibration environments such as ships and construction machinery, it is recommended to use spring terminals (models with the suffix "C", such as 787512), which have better vibration resistance than screw terminals.

Fixed special values: If precise 0.5s or 10s are required and on-site personnel do not want to make incorrect adjustments, fixed delay models (777514, 777517) can be selected.

Detailed explanation of functional principles and operating modes

3.1 Internal Logic and Terminal Definition

Refer to the block diagram (page 9 of the manual), the key terminals are as follows:

Terminal group symbol function

Power supply A1, A2 24V DC (A1 positive, A2 negative)

Input circuit S11, S12, S21, S22, S31, S32 emergency stop or safety door signal input. When using dual channels, S11-S12 and S21-S22 need to be used in pairs (with cross short circuit detection, S31-S32 assistance is required).

Start circuits S13 and S14 are used for monitored startup (if automatic startup is used, S13-S14 must be short circuited)

Feedback loops Y39 and Y40 are used to monitor external contactors or expansion modules to ensure that they actually open after the safety contacts are disconnected

The delay setting front panel knob is only available in adjustable versions and is used to set the delay TV (selected by scale)

Instantaneous outputs 13-14, 23-24, 33-34 immediately disconnect

Delay output 47-48, 57-58 delay disconnect

3.2 Workflow

Power on: POWER LED lights up.

Waiting ready: Start circuits S13-S14 are closed (if using monitored start, an additional 300ms of waiting time is required before closing the start circuit). During automatic startup, S13-S14 will be permanently short circuited.

Input circuit closed (e.g. emergency stop not pressed):

The internal relay is closed, and the instantaneous safety contacts 13-14, 23-24, and 33-34 are closed.

Delay contacts 47-48, 57-58 immediately close and start timing? No: The delay contact closes immediately when the input is closed and opens with a delay only when the input is disconnected. The manual clearly states: "Safety contacts 47-48 and 57-58 close when the input circuit is closed, and open after the delay time has expired when the input circuit is open." Correction: Delay contacts close immediately when the input is closed and only open after the input is disconnected via TV.

CH.1, CH.2, CH.1 [t], CH.2 [t] LEDs are all on. The START LED will turn off after the startup is completed.

Input circuit disconnected (press emergency stop):

Instantaneous contact opens immediately.

The delay contact remains closed to start the delay TV. After the TV ends, the delay contact opens and the CH.1 [t] and CH.2 [t] LEDs turn off.

Reset: To restart, the input circuit must be restored to closed, the delay time has ended, and the conditions for starting the circuit are met.

3.3 Special Function: Early Termination Delay

During the delay process, if the starting circuit (Y39-Y40) is disconnected, the delay can be terminated in advance and the delay contact can be immediately opened. This can be used for "canceling delay" in emergency situations. Just string a normally closed contact into the Y39-Y40 circuit.

Installation and wiring specifications

4.1 Mechanical Installation

Environmental temperature: -10 ℃~+55 ℃; Humidity 93% @ 40 ℃ without condensation.

Protection level: enclosure IP40, terminal IP20, installed in control cabinet (IP54).

Installation method: 35mm DIN rail, can be installed horizontally or vertically. Use the buckle on the back of the module to secure it.

Dimensions: Width 45mm, height 94mm (screw terminal) or 101mm (spring terminal), depth 121mm.

4.2 Power supply and input circuit wiring

Power supply: 24V DC, tolerance -15%/+10% (i.e. 20.4V~26.4V). Residual ripple ≤ 160% (≤ 38.4V peak). Power consumption of 4.5W. A power supply that complies with SELV/PELV standards must be used, and 0V must be grounded (to provide a ground fault detection reference).

Input circuit: Select the wiring method according to the safety level.

Wiring method: Terminal connection, maximum total cable resistance (Rmax), detection capability

Single channel S11-S12 short circuit, S21-S22 short circuit, using only one pair (such as S11-S21) 100 Ω ground fault

Dual channel no cross short circuit detection S11-S12 connected to one contact, S21-S22 connected to the other contact, no additional detection line 100 Ω ground fault or short circuit

The dual channel cross short circuit detection uses S11, S12, S21, S22, S31, S32 (see manual diagram for specific wiring), and requires additional connections of 10 Ω such as S22-S32 to detect cross short circuits between the two channels

Important: For wiring with cross short circuit detection, the maximum cable resistance is only 10 Ω. If the cable is too long, it may cause the fuse to fail to trigger within the specified time. The manual recommends performing the following tests after installation:

Keep the unit in working condition (with safety contacts closed).

Short circuit test terminals S22 and S32.

The internal fuse should activate within 2 minutes and the safety contacts should open.

Remove the short circuit and power off for about 1 minute to reset.

Start circuit:

Auto start: A jumper must be used to short circuit between S13 and S14.

Monitoring start: S13 is connected to the normally open button, S14 is connected to the other end of the button. The minimum width of the starting pulse is 30ms, and it must wait for 300ms after the input circuit is closed to effectively start (to avoid false triggering).

Feedback loop: Y39-Y40 should be connected in series with external contactors or normally closed auxiliary contacts of PZE expansion modules to confirm that the load has actually been disconnected. If no feedback is needed, Y39-Y40 must be short circuited.

4.3 Output contact fuse protection

To prevent contact welding, suitable fuses or circuit breakers must be connected in series in each output circuit. Recommended value:

Contact type: fast fuse, slow fuse, gG fuse, circuit breaker (B/C characteristics)

Instantaneous/Delay Safety Contact 10 A 6 A 10 A 6 A

Contact Capacity Comparison:

AC1 (resistive, 240V): maximum 8A, 2000VA

AC15 (inductive, 230V): maximum 5A

DC13 (inductive, 24V, 6 times/minute): maximum 7A

DC1 (resistive, 24V): maximum 8A, 200W

When multiple channels are loaded simultaneously, the total thermal current needs to be reduced. For example, using three contacts to conduct electricity simultaneously, the allowable thermal current for each contact is 5.5A (under 24V DC/AC1 conditions); Reduce to 4.3A using 5 contacts.

4.4 Cable length calculation

The maximum cable length is determined by the resistance limit:

Lmax=Rmax/(Rl/km)

For example, using a 1.5mm ² copper cable (with a resistance of approximately 12.1 Ω/km), the maximum length under a single channel of 100 Ω is approximately 8.26km (actually limited by distributed capacitance, but still far greater than typical on-site distances).

For cross short circuit detection (Rmax=10 Ω), the maximum length under the same wire diameter is ≈ 826m. If the on-site distance exceeds this value, the wire diameter needs to be increased or a relay needs to be used.

4.5 EMC and Wiring Points

The input, startup, and feedback loop cables should be routed separately from the power cables (frequency converters, motors, contactors), with a spacing of ≥ 200mm or using shielded cables.

Inductive loads (relays, contactor coils) must be equipped with suppression circuits at both ends of the contacts: RC absorption for AC and freewheeling diodes for DC (note diode polarity), otherwise it will seriously shorten the contact life.

It is not allowed to use the same contact for small currents (such as a few milliamps) after switching excessive currents, otherwise the signal may be unreliable due to increased contact resistance.

Delay configuration and startup mode setting

5.1 Adjustable Delay Setting (777510/777512/777518 and Spring Terminal Version)

The front panel has a knob engraved with multiple gears. Different gear types correspond to different delay values:

777510/787510 (0~30s gear): 0.1, 0.5, 1, 2, 4, 6, 8, 10, 15, 20, 25, 30 seconds.

777512/787512 (0-3s gear): 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 1, 1.5, 2, 3 seconds.

777518/787518 (0~300s gear): 0.3, 5, 10, 20, 40, 60, 80, 100, 150, 200, 250, 300 seconds.

Setting method: Use a small flathead screwdriver to rotate the knob to the desired scale. Attention: If the knob is located between two scales, the delay value may not be accurate. Is it strictly prohibited to rotate while powered on? The manual does not explicitly prohibit it, but it is recommended to set it after power failure.

Fixed delay models: 777514 (0.5s), 777517 (10s) without knob, internally fixed.

5.2 Startup Mode Configuration

Determine the startup mode through wiring:

Auto start: Short circuit S13 and S14 (which may have been short circuited at the factory). After the input circuit is closed, the unit will automatically activate the output after a delay of about 350-650ms (switch on delay).

Monitor start: Connect a normally open button (reset button) between S13 and S14. After the input circuit is closed, the button needs to be pressed for at least 30ms and must wait for 300ms (waiting period) after the input is closed before it can take effect. This can prevent unexpected restarts caused by input jitter.

Detection: In the monitored startup mode, if the reset button is not pressed after the input circuit is closed, the START LED will not light up and the safety contacts will not close.

Safety characteristic data and contact life

6.1 Security Level (from page 33 of the manual)

According to EN ISO 13849-1 and EN IEC 62061, the characteristics of PNOZ XV3P are as follows:

Operating mode PL Category SIL CL PFH_D [1/h] T-M [year]

Instantaneous safety contact PL e Cat.4 SIL 3 2.31E-09 20

Delay safety contact (TV<30s) PL d Cat. 3 SIL 3 2.64E-09 20

Delay safety contact (TV ≥ 30s) PL c Cat. 1 SIL 1 2.87E-09 20

Important: The longer the delay time, the lower the security level may be. When using a delay of more than 30 seconds, the risk should be reassessed (PL reduced to c). The above data is the contribution value of the module itself, and the overall safety function level needs to be calculated based on the basic unit and external wiring. It is recommended to use Pilz PAScal software.

6.2 Contact life diagram

The manual provides contact life curves for AC15 and DC13 loads (page 34). For example, under a 230V AC15 load and a switching current of 0.2A, the contact life is approximately 4 million times. The larger the current, the shorter the lifespan (such as about 100000 cycles at 5A).

Measures to extend lifespan:

Suppression circuits (RC/diodes) must be used for inductive loads.

If the expected lifespan caused by the actual switching frequency and load current is lower than the service life of the equipment, consideration should be given to using larger capacity contactors as intermediate amplifiers or using PZE expansion modules to share the current.

The manual states that if life curve data cannot be obtained, the given PFH value can be directly used for calculation, but it is only valid when the expected number of switches is lower than the corresponding value in the curve.

Common troubleshooting

7.1 Fault phenomenon: POWER LED lights up, but there is no output after closing the input circuit (START LED does not light up, contacts do not engage)

Possible reasons:

The startup circuit is not closed (S13-S14 open circuit and configured for monitored startup) or the automatic startup short circuit is missing.

Feedback loop Y39-Y40 is open (e.g. not short circuited or external expansion module failure).

Input circuit wiring error (mismatch between single/dual channel configuration and actual wiring).

The power supply voltage is below 20.4V.

Troubleshooting steps:

Measure the voltage of A1-A2, which should be ≥ 20.4V.

Check S13-S14: If it is an automatic start, the resistance should be measured to be approximately 0 Ω; If it is a monitored startup, it should conduct when the button is pressed.

Short circuit Y39-Y40 (temporary) test. If it returns to normal, check the external feedback contactor or PZE expansion module.

Check the voltage of the two channels in the input circuit: When the safety switch is closed, S11-S12 should conduct (close to 0V voltage drop), and S21-S22 should do the same. If using dual channel with cross short circuit detection, it is also necessary to check the S31-S32 connections.

If all wiring is correct, it may be an internal fault, replace the module.

7.2 Fault phenomenon: After the input is disconnected, the instantaneous contact opens normally, but the delayed contact does not open or opens very slowly

Possible reasons:

The delay setting knob was mistakenly turned to the "0" or infinite position.

Delay circuit capacitor aging (rare, but may occur after years of use).

Excessive load current leads to contact fusion welding, causing the delayed contact to still adhere when it should be opened.

troubleshoot

Check the knob scale and confirm the set value. If the knob is damaged, use a screwdriver to readjust and observe if the delay changes.

After the input is disconnected, use a multimeter to measure the resistance across the delay contacts 47-48: the strain becomes infinite after the expected opening time. If it is still conductive (<1 Ω), the contact has been welded. Replace the module and check if the external load is short circuited or if the suppression circuit is malfunctioning.

Refer to the manual for delay accuracy (-15%/+15%+50ms). If the actual measured delay deviates from the set value beyond this range and the set error is excluded, the module may malfunction.

7.3 Fault phenomenon: POWER LED off or flashing

Reason:

Power loss or low/high voltage.

Power surge causes internal fuses to burn out (rarely).

handle:

Measure the voltage of A1-A2. If the voltage is 0, check the higher-level circuit breaker, fuse, and wiring.

If the voltage is normal but the LED still goes out, it may be due to internal damage to the module. Try turning off the power for 1 minute and then turning it back on. If it still doesn't light up, replace the module.

7.4 Fault phenomenon: After the input circuit is closed, the safety contact briefly closes and then immediately disconnects (self trips)

Possible reasons:

There is loose wiring or contact jitter in the input circuit.

The cross short circuit detection function is triggered (for example, there is leakage resistance between two channels).

The feedback loop is briefly interrupted during the startup process.

troubleshoot

Quickly record the input channel voltage using an oscilloscope or multimeter. If interruptions are found in S11-S12 or S21-S22, check the emergency stop button contacts or wiring terminals.

If using dual channel cross short circuit detection, check the insulation resistance between S22-S32 (should be>100k Ω). If there is low resistance (such as water ingress into the cable), the module will detect a "suspected jumper short circuit" and lock it.

Check if there is an instantaneous open circuit caused by vibration in the Y39-Y40 circuit.

7.5 Fault phenomenon: Unable to start after pressing the reset button in the monitored startup mode

Possible reasons:

The input circuit has not been closed yet.

After the input circuit is closed, there is no waiting period of 300ms.

The reset pulse width is less than 30ms (e.g. hand press time is too short).

The resistance of the S13-S14 connection line is too high.

verification:

Ensure that the input circuit is closed and stable (CH.1/CH.2 LED should be on). If not, please handle the input circuit first.

Press the reset button for at least 0.5 seconds (>30ms), wait for a moment (up to 700ms switch on delay), and see if the output is engaged.

Use a multimeter to monitor the resistance of S13-S14 when pressed, which should be close to 0 Ω.

7.6 Grounding Fault Detection and Recovery

PNOZ XV3P can detect short circuits to ground in input circuits or startup circuits. When a ground fault occurs locally, the module will shut down the output (safety contacts open), the POWER LED may turn off or the ERR indicator may be displayed (the manual does not specify a separate ERR light, but it is indicated by the POWER turning off). Recovery steps:

Eliminate grounding faults (use an insulation resistance tester to find the grounding point).

Disconnect the power for about 1 minute (reset the internal protection circuit).

Re power on, if the fault has been resolved, the module should return to normal.

Regular Inspection and Maintenance Plan

According to EN ISO 13849-1, safety functions must be regularly tested to confirm proper functioning:

Frequency of required safety level inspection

PL e/SIL 3 at least once a month

PL d/SIL 2 at least once a year

Inspection steps (applicable to PNOZ XV3P):

Trigger the input circuit (such as pressing the emergency stop button or opening the safety door).

Confirm that the load corresponding to the instantaneous safety contact stops, and the load corresponding to the delay contact stops after the set delay.

Reset the emergency stop and execute the startup program (such as pressing the reset button).

Confirm that all loads are powered on again.

If it cannot be restarted during the reset process, it indicates that a fault has been detected internally or externally (such as contact welding or abnormal feedback loop), and the above-mentioned troubleshooting should be carried out.

Annual in-depth maintenance:

Check the torque of all terminal screws (0.5Nm), spring terminals do not require torque but need to be checked for complete insertion.

Clean the cabinet dust and check for water stains or corrosion.

If the module has been running for more than 20 years (TM), replacement should be considered, even if it still works.

Common errors and avoidance

During automatic startup, monitored startup wiring was used: forgot to short-circuit S13-S14, causing the unit to fail to start. Solution: In automatic start mode, it is necessary to permanently short-circuit S13-S14.

Unused feedback loop: Y39-Y40 open circuit causes the output to never close. If external expansion is not used, Y39-Y40 must be short circuited with jumper wires.

Double channel cross short circuit detection wiring error: The common terminals of two channels were mistakenly connected together, causing the detection function to malfunction. Strictly follow the wiring instructions in the manual to ensure that there is no direct short circuit between S22 and S32 (except during testing).

The contact fuse is too rough to keep the contact continuously open during welding: using a 10A slow speed fuse may still fail to effectively protect under AC15 load of 5A. Recommended specifications (6A slow speed or 10A fast melting) must be used. For inductive loads, the breaking capacity of the fuse should be sufficient.

Neglecting environmental temperature: Using in environments exceeding 55 ℃ may result in a shortened lifespan of internal electronic components. Similarly, temperatures below -10 ℃ may not start.

Delay setting not validated: There is an error of+/-15% in the adjustable delay. For time critical applications, a timer should be used to measure the actual breaking time, and if necessary, a setting that is close but slightly shorter should be selected.