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NIDE Machine Safety Standard — C1/C2

Establishes required conditions to comply with C1 and C2 Customer Safety Requirements for all machines and equipment delivered by NIDE. Based on ISO 12100 principles. Must ALWAYS be followed when a new project starts.

NIDE 00001 Revision 01 01/09/2014 Roberto A. Schöpf C1 / C2 Customers
🎯 Objective
Establishes required conditions for C1 and C2 customers. Applies to ALL machines delivered by NIDE. Any deviations must be agreed upon by customers before the machine production phase. Does not replace ISO 12100 — ISO 12100 has priority.
⭐ Design Target: Category 4 / PL e
Always design for Category 4 / Performance Level "e" — the safest machine configuration. Only reduce category when cost impacts are significant and only after discussion with Project Coordinator/Chief Engineer.
📋 What This Standard Covers
Guards, emergency stops, light curtains, safety door interlocks, safety pneumatic valves, safety relays, STO (servo drives), LOTO, grounding, exhaust systems, warning identifications.
🏭 Scope of Application
All machine/equipment delivered to C1 and C2 customers. Safety Engineer evaluates category compliance at installation. Non-compliant machines will not be approved for production.
Risk Assessment
Safety Category Calculator
Select the severity (S), frequency of exposure (F), and probability of avoidance (P) parameters to determine the required safety category and performance level. NIDE always targets Category 4 / PL e.
S — Severity of Injury
F — Frequency & Duration of Exposure to Hazard
P — Probability of Avoiding or Limiting Harm
1

Category 1 / PL a

Low risk. Well-tried safety components and principles. Standard single-channel architecture sufficient. Basic safety measures required.

Cat 1-2 / PL a-b
Low risk. Slight injuries with low exposure. Standard components, single channel architecture. Basic safety principles sufficient.
Cat 3 / PL c-d
Medium-high risk. Single fault must not cause loss of safety function. Dual-channel architecture with monitoring. Frequently required.
Cat 4 / PL e — NIDE TARGET ⭐
Highest risk. Fully redundant. No single or accumulated fault causes loss of safety. Individual wiring per device mandatory. Pressing, cutting, robots.
Safety Devices
Interactive Device Reference
Each safety device required by the NIDE standard — specifications, installation rules, and an interactive simulation of its behavior when activated.

🔴 Emergency Stop Button

Immediate cessation of all hazardous machine functions. Must override all other machine controls. Pressing E-Stop must never by itself restart the machine — a separate manual action is always required.

  • Color: Red with Yellow background
  • Size: 22mm or 30mm diameter
  • Contacts: 2NC (Normally Closed), self-monitoring
  • Type: Latched — requires manual release (pull-out or rotate)
  • NOT momentary/spring-return type
  • Minimum Category: 4 — connected to safety relay
  • Stop Category 0 or 1 per risk assessment
  • Recommended: Schneider XB5AS8444
🟢 MACHINE RUNNING
Emergency Stop
1
E-Stop pressed → 2NC contacts open
2
Safety relay receives signal → triggers stop
3
Stop Cat 0: power removed from actuators immediately
4
Safety valve closes → air pressure cut
5
STO activated on servo drives → no torque
6
Safe state maintained — no automatic restart possible

🟡 Safety Light Curtain

Optoelectronic protective device (IEC 61496-1). Detects interruption of infrared beams. Generates OSSD signal to safety system. Must be Category 4.

  • Minimum distance to hazard: >250mm (NIDE standard)
  • Inspection criterion: >350mm from closest risk area
  • Distance depends on curtain response time and resolution
  • Output: OSSD (PNP or NPN) to safety relay
  • Stop Category 0 or 1 per risk assessment
  • Manual reset required after breach is cleared
  • Recommended: SICK C4C / C4P series
Move cursor / hover over beam area
✓ Curtain Clear — Machine Running

🚪 Safety Door Interlock

Required in any area accessed for maintenance, adjustments, or material/model setup. Category 4: individual wiring — never connect interlocks in series.

  • Individual wiring between each interlock and safety relay (not series)
  • Category 4: PSENbolt + PSENcode cs3.1 (redundant)
  • Standard: Pilz PSEN 6L000018 / PSEN 6L000004
  • On door open: motors lose power or STO activates + air cut
  • Door cannot open in automatic mode
  • Must select manual mode first, then press door open button
  • Manual reset required after door is closed
MACHINE 🔒 DOOR
Door Closed
Motors Active
Air OK
Running

💨 Safety Pneumatic Valve

Installed at the machine's pressured air entry. Connected to safety relay — cuts air pressure when any safety device is activated. Active in both manual and automatic mode.

  • Location: air entry point of the machine (input position)
  • Connected to: safety relay output
  • Triggered by: E-Stop, door interlock, light curtain, safety sensor
  • Switching positions monitored by proximity (inductive) sensors
  • Sensor signals compared with control signals → discrepancy = safety response
  • Vertical load cylinders: pilot-operated check valves (HGL) required to prevent drop
  • Recommended: Festo VOFA-L26-T32C-M-G14-1C1-APP
AIR IN SAFETY VALVE POSITION SENSOR SAFETY RELAY CYLINDER OPEN — Air flowing HGL CHECK VALVE

⚙️ STO — Safe Torque Off

Mandatory for C1 and C2 customers. STO disables the motor's ability to generate torque by blocking the power stage — it is different from simply cutting power.

  • Mandatory: servo drivers with STO for all C1/C2 machines
  • STO ≠ power cut: power stage blocked, motor cannot generate torque
  • Motor cannot rotate but does not enter an uncontrolled state
  • Manual mode: speed must be limited, configurable in HMI (password-protected)
  • STO: Siemens V90 — 6SL3210-5FB10
  • Without STO (relay cutoff): Delta ASD-A3-5523-F
Motor running — torque being generated

🔌 Safety Relay

All safety devices must connect to a Category 4 safety relay. Dedicated component — does not replace PLC. Monitors all safety devices simultaneously.

  • Category: 4 (mandatory for C1/C2)
  • Monitors: E-Stop, guard interlocks, light curtains, two-hand controls, speed, position
  • Cat 4: individual wiring required — NO series connection of multiple interlocks
  • Functions: E-Stop monitoring, guard monitoring, light curtain monitoring, speed monitoring
  • Recommended: Pilz PNOZ c1 24VDC 3n/o 1n/c / PNOZ c2 24VDC 2n/o
SAFETY RELAY CAT 4 E-STOP LIGHT CURTAIN DOOR INTERLOCK SAFETY SENSOR MOTOR (STO) PNEU. VALVE CONTACTOR INPUTS OUTPUTS

🔒 LOTO — Lockout Tagout

Protection system against unintentional exposure to hazardous energy. Only the person who cuts off energy can turn it back on — ensures exclusive control during maintenance.

  • Applies to: main electrical power, pneumatic supply, hydraulic, any hazardous energy source
  • Required in: machine operational manual (safety instructions)
  • LOTO procedures must be available in customer's local language
  • Evidence required: picture showing LOTO for main power key and pneumatic valve
  • Only the person who locked out can unlock — key stays with the technician
MAIN POWER OFF 🔒 LOCKED OUT PNEU. VALVE OFF 🔒 LOCKED OUT LOTO TAG — TECHNICIAN: ____________ DATE: ______ KEY WITH TECHNICIAN 🔑
Outcomes
Expected Outcomes When Safety Devices Activate
Required behavior when each safety device is triggered. All follow the same principle: immediate cessation → safe state → manual reset required to re-enable.
🔴 Emergency Stop — Activation Sequence
Step 1
🔴
E-Stop Pressed
Operator presses button. 2NC contacts open. Latched — manual release required.
Step 2
⚡
Safety Relay Trips
Relay receives open-circuit → triggers stop command to all outputs simultaneously.
Step 3
💨
Air Pressure Cut
Safety valve closes. Cylinders de-energized. HGL check valves hold vertical loads.
Step 4
⚙️
Motors Stop
STO activated on servo drives. Contactors open on induction motors. No torque.
Step 5
✅
Safe State
All hazardous motion stopped. Machine remains safe. No automatic restart possible.
Step 6
🔑
Manual Reset
Operator releases E-Stop (pull/rotate), then presses Reset button to re-enable.
🟡 Light Curtain — Beam Interruption Sequence
Step 1
✋
Beam Interrupted
Operator crosses curtain in automatic mode. Infrared beam blocked.
Step 2
📡
OSSD Signal
Curtain sends OSSD change to safety control system → breach detected.
Step 3
🛑
Functions Stop
Cat 0 or Cat 1 stop — power removed from actuators. All motion ceases.
Step 4
✅
Safe State
Machine in safe state while operator is in risk area. No restart possible.
Step 5
🔑
Reset Required
Exit risk area → curtain clears → press manual reset to re-enable machine.
🚪 Safety Door Interlock — Door Open Sequence
Step 1
🚪
Door Opens
Safety door opened. Interlock switch detects door position change.
Step 2
⚡
Controlled Stop
Safety relay initiates stop (Cat 0 or 1 per risk assessment).
Step 3
💨
Air & Power Cut
Motors lose power or STO. Air cut via safety valve.
Step 4
✅
Safe State Held
Safe state maintained while door is open. No automatic restart possible.
Step 5
🔑
Close + Reset
Close door → press manual reset to re-enable. Reset does not start machine.
⛔ Stop Category 0
Immediate removal of power to machine actuators → uncontrolled stop. Used when fastest stop is needed and abrupt stop does not create secondary hazards.
🔶 Stop Category 1
Controlled stop with power available to decelerate, followed by power removal. Used when abrupt stop could cause secondary hazards (heavy loads, high-speed axes, robots).
Calculators
Safety Distance Reference
Interactive lookup tables from NIDE Safety Standard Tables 1 and 2. Determines required safety distances based on guard geometry and opening dimensions.
Minimum horizontal distance "c" (mm) when reaching over a fixed guard. General rule: guard must be minimum 1800mm high. sd = safety distance method required when guard height alone is insufficient.
800 mm
Minimum horizontal safety distance "c" between guard and hazard zone
Minimum safety distance "sd" when reaching through an opening in a guard. "e" = smallest dimension of the opening (diameter for round, side for square, width for slot).
166 mm
Minimum safety distance "sd" required
NIDE minimum: >250mm. Inspection criterion: >350mm from closest risk area. Exact distance depends on curtain response time and resolution per ISO 13855.
350 mm
Estimated minimum safety distance (verify with SICK/Pilz tool)
ISO 13855 formula: S = K × (ts + tr) + C  |  K = 2000 mm/s (hand speed), C = 8×(d−14) mm when d > 14mm. Always verify with SICK safety distance calculator or Pilz PAScal tool. NIDE minimum is 250mm; inspection checklist requires 350mm.
Annex B
Machine Safety Inspection Checklist
34-item safety inspection checklist for C1/C2 machine acceptance. Each item requires evidence before machine approval for production. Track completion below.
0 / 34 completed
Annex A
Recommended Safety Components
When not specified by the customer, use these components to ensure compliance with NIDE safety standards and international requirements.
Safety Relay — Pilz PNOZ
Safety Relay — 3NO 1NCPNOZ c1 24VDC 3n/o 1n/c
Safety Relay — 2NOPNOZ c2 24VDC 2n/o
Safety Door Key — Pilz PSEN
Safety door key (standard)PSEN 6L000018
Safety door key (standard)PSEN 6L000004
Safety door key — Category 4PSENbolt + PSENcode cs3.1
Emergency Stop — Schneider Electric
E-Stop 2NC (40mm mushroom)XB5AS8444
Servo Drives (with STO)
Siemens V90 — with STO6SL3210-5FB10
Delta — without STO (relay cutoff)ASD-A3-5523-F
Light Curtain — SICK C4 Series
Sender (P-type)C4P-SA07511A00
Receiver (P-type)C4P-EA07511C00
Sender (C-type)C4C-SA07510A10000
Receiver (C-type)C4C-EA07510A10000
Sender (SC-type)C4C-SC07510A10000
Receiver (EC-type)C4C-EC07510A10000
Safety Pneumatic Valve — Festo
Safety valve G1/4 — 1C1VOFA-L26-T32C-M-G14-1C1-APP
Safety Sensor — Pilz
Safety sensorPSEN ma2.1p-31 / PSEN2.1-10