Phoenix Contact PSR-SPP-24DC/RSM4/4X1 Safety Relay

Phoenix Contact Order No. 2981541

1. Basic Information

Brand: Phoenix Contact (the spelling “phonex” mentioned is a typo)

Full Model: PSR-SPP-24DC/RSM4/4X1

Material Order Number: 2981541

Product Positioning: Dual-channel speed monitoring safety module, specially designed for motor overspeed/zero-speed monitoring, belonging to the PSR-TRISAFE safety series

2. Model Code Definition

3. Core Safety Certification Levels (Key Parameters)
4. EN ISO 13849: PL e / Category 4 (Highest machinery safety level)
5. IEC 61508 / IEC 62061: SIL 3
6. Stop Category: Category 0 safety cut-off per EN 60204-1
7. Contacts: Force-guided safety contacts compliant with IEC/EN 61810-3, mechanical service life ＞ 50 million operations
8. Electrical and Mechanical Specifications

4.1 Power Supply Input

Rated Voltage: DC 24V, allowable range: 20.4~26.4V

Rated Input Current: 100mA

4.2 Speed Measurement Input (Dual-channel IN1/IN2)

Supported sensors: Incremental encoders, proximity switches, Hall effect sensors

Max. Input Frequency: 2kHz

Typical Response Time: 15ms; Release Time: 12ms; Recovery Delay: 1s

4.3 Safety Output

4 independent normally-open safety contacts (4PST-NO)

Contact Rating: 250V AC / 5A

4.4 Mechanical Dimensions

Width: 45mm, Height: 112mm, Depth: 114.5mm

Mounting: Standard 35mm DIN rail

Wiring: Plug-in spring-cage terminals

Protection Class: IP20 (for cabinet internal installation only)

Operating Temperature: -20℃ ~ +55℃; Storage Temperature: -40℃ ~ +70℃

4.5 Configuration Interface

Built-in front-side RJ45 Ethernet port. The supporting software PSR-RSM4 enables online parameter setting via PC, including overspeed threshold, zero-speed threshold, delay time, dual-channel verification logic and fault diagnosis parameters.

5. Typical Application Scenarios
6. Lifting equipment and winches: Prevent drum runaway caused by overspeed
7. Fans and centrifuges: Overspeed protection and emergency stop
8. Conveyors and roller motors: Safety door unlocking after zero-speed confirmation
9. Machine tool spindles and rotating tooling: Dual-channel redundant speed safety monitoring

Advantags: Dual-channel redundant detection maintains safe cut-off even if one channel fails, complying with machinery safety regulations for equipment.

6. Function Overview
7. Dual-channel redundant speed measurement: Compare signals from two encoders to avoid failure risks from open/short circuit of a single channel
8. Two operating modes:

Overspeed protection: Immediately cut off safety outputs when rotation speed exceeds preset threshold

Zero-speed monitoring: Judge stationary state when speed drops below threshold and allow safety door unlocking

3. Fault diagnosis: Read fault codes via Ethernet port (open circuit, short circuit, speed out of limit, channel deviation)
4. Safety feedback loop: Supports monitoring of external contactor auxiliary contacts to prevent contact welding failure
5. Supporting Products & Alternative Models
6. Configuration Software: PSR-RSM4 (free download on Phoenix Contact official website)
7. Distinction of alternatives within the same series:

2981541: Programmable speed monitoring with Ethernet port, 4 normally-open contacts

PSR-SPP-24DC/ESD: General safety relay for emergency stop / safety door, without speed monitoring function

3. HS Customs Code: 85364900 (Electromagnetic safety relays)
4. Procurement Notes

EAN Barcode: 4017918996833

EMC Class: Class A (For industrial environments only, not applicable to civil weak-current environments)

Standard Packaging: Single unit per box, 12-month original manufacturer warranty

Complete Working Principle of Phoenix Contact PSR-SPP-24DC/RSM4/4X1 (2981541) Speed Monitoring Safety Relay

This unit is a TRISAFE programmable dual-channel speed safety module. Its core design adopts a triple safety architecture: Fail-Safe principle + dual-channel redundant speed detection + force-guided safety outputs. It integrates programmable overspeed/zero-speed logic, full-circuit self-test and contactor feedback monitoring, achieving the highest safety rating of PL e / Cat.4 / SIL 3.

1. Hierarchical Overall Hardware Architecture (Input to Output)

The unit consists of 4 independent isolated modules:

1. DC24V Power Supply Unit (Terminals A1/A2): Power supply for the whole device and internal self-test circuit
2. Dual-channel Speed Input Unit (IN1, IN2): Two fully independent circuits for collecting rotation pulse signals
3. Dual-core Safety Logic Processing Unit (with RJ45 configuration port): Hardware comparison of dual signals, threshold judgment and fault diagnosis
4. 4-channel Force-guided Safety Relay Output Unit: Divided into two isolated safety loops (emergency stop cut-off + safety door unlock enable), equipped with external contactor feedback monitoring circuit
5. Step 1: Working Principle of Dual-channel Speed Signal Acquisition (Core Redundant Detection)

2.1 Supported Sensor Types

Dual-channel incremental encoders (A/B phase quadrature pulses)

Two independent NPN/PNP proximity switches, Hall effect speed probes

IN1 and IN2 inputs feature complete electrical isolation and separate sampling circuits to realize dual-channel redundant verification, eliminating safety hazards caused by open circuits, short circuits or single probe failure.

2.2 Calculation Logic: Convert Pulses to Rotation Speed

Sensors output frequency pulses synchronously with motor shaft rotation (max. 2kHz). Internal hardware counters capture pulse frequencies of both channels in real time and convert them to actual rotation speed via the formula:

2.3 Dual-channel Consistency Verification (Core Safety Feature)

The logic unit continuously compares converted speed values from IN1 and IN2:

If speed deviation between two channels is within software-set tolerance → Signals are deemed valid

If single channel open/short circuit, pulse loss or excessive channel deviation is detected → Speed circuit fault is triggered instantly, all safety outputs are cut off and fault state latched

> Safety implication: Single-channel faults cannot mask overspeed risks, meeting machinery safety redundancy requirements.

3. Step 2: Programmable Safety Logic Judgment (Dual Modes: Overspeed / Zero-speed)

Two groups of thresholds are preset via connecting a PC with PSR-RSM4 software over RJ45 port. The module compares real-time measured speed against thresholds and operates under two modes:

Mode 1: Overspeed Protection (For winches, centrifuges, spindle runaway prevention)

1. Measured speed ＞ Software-set overspeed threshold
2. Internal dual-core safety circuitry immediately de-energizes coils of two groups of safety output relays
3. All 4 normally-open safety contacts are forced open within 15ms to cut off main motor contactor and servo enable loops
4. Fault state latches; power cycle reset or external reset terminal must be used to clear fault before resuming operation

Mode 2: Zero-speed Monitoring (Safety door / maintenance door interlock)

1. Measured speed ＜ Software-set stationary zero-speed threshold and held for preset delay duration
2. The second group of safety contacts remains closed to output a safety door unlock enable signal, allowing access to machine guard doors
3. Once minor shaft rotation occurs and speed exceeds zero-speed threshold, enable contacts open within 12ms to lock safety doors and prevent personnel entanglement with rotating components

Additional Logic: External Contactor Feedback Monitoring (EDM Loop)

Auxiliary normally-closed contacts of the main contactor are wired to dedicated terminals for continuous monitoring:

Normal closed safety outputs → Contactor energized, feedback contacts open, logic confirms normal status

Welded output contacts or stuck contactor that cannot open → Abnormal feedback loop detected; module latches in safety cut-off state to eliminate runaway risks from contact failure

4. Step 3: Execution Principle of Force-guided Safety Outputs (IEC 61810-3)

The module integrates 4 independent force-guided safety relays, split into two isolated safety loops:

1. Terminals 13-14, 23-24: Overspeed emergency stop cut-off loop (controls main power contactor)
2. Terminals 33-34, 43-44: Zero-speed safety door enable loop (guard door unlock interlock)

Safety Mechanism of Force-guided Contacts (Distinguished from Ordinary Relays)

A mechanical linkage binds normally-open and normally-closed contacts of the same relay:

If normally-open contacts are welded closed by electric arcs and fail to open, the mechanical linkage mechanically restrains corresponding normally-closed contacts from closing

Auxiliary alarm contacts MO1/MO2 switch state upon output faults to transmit fault codes to PLC

This design guarantees that any single-point component failure forces outputs to the open (safe) state, complying with the Fail-Safe principle.

5. Principle of Full-unit Periodic Self-test & Fault Diagnosis

Continuous hardware self-test runs during power-up and full operation, covering the entire signal chain:

1. Input Loop Self-test: Detect IN1/IN2 short to 24V, short to 0V and open circuit
2. Internal Processing Unit Self-test: Mutual verification between dual cores; immediate shutdown if one chip malfunctions
3. Output Relay Self-test: Detect coil open circuit and contact welding (coordinated with EDM feedback)
4. Communication Self-test: Fault codes readable via RJ45 port: overspeed trigger, zero-speed loss, channel deviation, probe open circuit, contactor welding

Any fault detected during self-test triggers the following actions:

All safety output contacts open

Corresponding red fault LED on front panel illuminates

Fault state latches; manual reset or power restart required for clearance, no automatic restoration of dangerous output signals

6. Standard Complete Operating Flow (Normal Operation)
7. Apply DC24V power to A1/A2; unit completes full self-test, green run LED stays lit if no faults
8. IN1 and IN2 speed probes output synchronous pulses with consistent dual-channel readings
9. Measured speed below overspeed threshold → Emergency stop loops 13-14/23-24 stay closed, motor power supply permitted
10. Speed above zero-speed threshold → Safety door enable contacts 33-34/43-44 open, guard doors remain locked
11. Motor stops, speed drops below zero-speed threshold and holds preset delay → Enable contacts close, maintenance doors can be opened
12. If overspeed, single probe fault or contactor welding occurs during operation → All safety contacts open within 15ms, machine emergency stops and fault latches
13. Summary of Core Safety Principle (Single-sentence Overview)

Two fully independent hardware speed measurement channels collect rotation pulse signals; dual-core circuitry compares real-time speed with preset overspeed/zero-speed thresholds continuously. Combined with external contactor feedback monitoring, force-guided safety relays execute cut-off actions. Full-period self-test runs throughout operation, forcing all safety outputs open upon any single circuit or component failure. This delivers top-tier safety interlock protection to prevent rotating machinery runaway and allow guard door unlocking only when shafts are stationary.