Balluff BES 516-604-DZ-3 Delay Safety Relay for Industrial Timing
The Balluff BES 516-604-DZ-3 is a delay-on-release safety relay designed for industrial control circuits that require a timed shutdown or delayed restart function in safety-related applications. It combines the functionality of a conventional time delay relay with forced-guided (positive-guided) contacts, complying with safety categories up to SIL 2 (IEC 61508) and PL d (ISO 13849-1). This device is typically used to monitor emergency stops, light curtains, or safety gates where a fixed time delay is needed before power removal or reapplication.
Adjustable Delay Timing
The BES 516-604-DZ-3 features an adjustable delay range from 0.1 to 30 seconds, set via two potentiometers (coarse and fine) or a digital switch on the front panel. The delay mode is fixed as “delay-on-release” (also known as off-delay or power-off delay): when the safety input (Y1-Y2) is opened, the relay output remains energized for the preset time before de-energizing. This is essential for applications such as stopping a motor after a guard is opened, allowing the machine to coast to a halt safely. Timing accuracy is ±5% of the set value over the full operating temperature range.
Forced-Guided Relay Outputs
Two normally open (NO) safety outputs (contacts 13-14, 23-24) and one normally closed (NC) auxiliary contact (31-32) are provided, all with positive-guided operation as defined in EN 61810-3. This design ensures that NO and NC contacts cannot be closed simultaneously in the event of a welded contact, enabling the monitoring circuit to detect failures. The NO contacts are rated at 6 A / 250 VAC (AC-15) and 4 A / 24 VDC (DC-13). The auxiliary NC contact is suitable for feedback to a safety controller.
Input Circuit and Monitoring
The safety input channel (Y1-Y2) accepts dry contacts or solid-state outputs with a test pulse tolerance of up to 1 ms. The device supports dual-channel wiring (redundant inputs) for higher safety integrity. A start/auto-restart selection is available via a jumper: in “monitored start” mode, the relay outputs will only energize after the input circuit is closed and a separate start button is pressed. The “auto-start” mode automatically resets the output when the input circuit is closed (delay applies only to opening). Cross-circuit short detection is included for wiring between Y1 and Y2.
Power Supply and Status Indicators
Operating voltage: 24 VDC (range 19.2 to 30 VDC), with reverse polarity protection. Power consumption is typically 3 W. LED indicators: green PWR (power on), yellow IN (input active), red ERR (fault or cross-wiring), and green OUT (output energized). The device also indicates timing progress via a blinking LED during the delay period. An internal fuse (500 mA slow-blow) protects against overcurrent; the module is self-resetting after fault removal and power cycle.
Safety Ratings and Certifications
Safety integrity level: SIL 2 (IEC 61508, EN 62061)
Performance level: PL d (ISO 13849-1)
Category: Cat. 3 (redundant structure)
Probability of dangerous failure (PFHd): 2.5 × 10⁻⁸ per hour
Mission time (TM): 20 years
The relay is certified by TÜV Rheinland and UL (UL 508 listing). EN 60947-5-1 and EN 60204-1 compliance ensure suitability for machinery safety circuits.
Mechanical and Environmental Data
Dimensions: 22.5 mm width, 99 mm height, 114.5 mm depth (DIN rail housing). Operating temperature: -20 to +55°C; storage: -40 to +85°C. Protection class IP20 (enclosure) and IP00 (terminals). The housing material is polyamide (PA6.6) with V0 flammability rating. Vibration resistance: 10 to 55 Hz, 0.35 mm amplitude. The relay is designed for 10 million mechanical operations and 100,000 electrical operations at rated load.
Typical Applications
The BES 516-604-DZ-3 is ideal for conveyor belt stop delays after a guard door opens, hydraulic press holding time, cooling fan run-on after machine stop, and brake control in lifting equipment. It is also used to debounce and delay the activation of safety light curtains to prevent false trips due to vibration. In packaging machines, it can delay the reclosing of a guard until a blade has fully retracted.
Wiring and Installation
Terminals are spring-clamp type for solid or stranded wire up to 2.5 mm². A removable bridge is provided for loop-through of supply to multiple modules. The device mounts on a 35 mm DIN rail (EN 60715). Minimum clearance between modules: 10 mm for ventilation. For safety category 3 applications, both channels of the emergency stop switch must be connected redundantly, and the feedback loop must include the auxiliary contact of the relay to detect welding faults.
Testing and Maintenance
Regular functional testing (every 12 months) is recommended per ISO 13849-1. A built-in test button can simulate input opening without actual switch actuation. The module records the number of delayed operations in an internal non-volatile counter (readable via diagnostic LED flashes). No periodic replacement of timing components is required because the delay circuit is fully electronic with no aging capacitors.
Ordering Data
Order code: BES 516-604-DZ-3. Accessories include a transparent label holder (BES 516-Z01), a screw terminal adapter (BES 516-A2), and a DIN rail end stopper. The product conforms to RoHS and REACH regulations. A detailed operating manual (Balluff 790533) provides wiring examples for different safety categories.
