Siemens 3rp2505-1bw30

By Abdullah Zahid
13 min read
Siemens 3RP2505-1BW30 SIRIUS multifunction timing relay with 27 switching functions mounted on DIN rail in industrial control panel

Siemens 3RP2505-1BW30 SIRIUS Timing Relay, Multifunction, 2 Changeover Contacts, 27 Functions, 7 Time Ranges (0.05 s to 100 h), 12-240 V AC/DC, 50/60 Hz, LED, Screw Terminal — Specifications, Selection Guide and Alternatives

Controls engineers specifying a timing relay for motor sequencing, conveyor delays, or machine dwell control often face the same problem: no single economy relay covers all the switching functions their application actually needs. The Siemens 3RP2505-1BW30 addresses that directly. It is a SIRIUS multifunction electronic timing relay offering 27 switching functions across 7 time ranges from 0.05 seconds to 100 hours, powered by any control supply from 12 to 240 V AC/DC at 50/60 Hz, and fitted with 2 changeover contacts rated at 5 A thermal current. For a panel builder or automation engineer trying to close out a BOM with one SKU instead of three, this is the model to evaluate carefully.

If you have already confirmed technical fit and just need to check stock and pricing, view the Siemens 3RP2505-1BW30 product page at LeadTime.ca — ships worldwide.

Who Should Buy the 3RP2505-1BW30 — and Who Should Not

This relay is the right choice for engineers who need a single, proven timing relay that handles mixed control voltages and covers most sequencing logic without additional modules. It is specifically a strong fit when all of the following are true:

  • Your control supply voltage is anywhere within 12-240 V AC/DC at 50/60 Hz — not a fixed 24 V DC-only system
  • Two changeover contacts at 5 A thermal current are sufficient to switch your downstream coil loads
  • Your fastest required timed pulse is no shorter than 35 ms (minimum ON period)
  • You need access to 27 switching functions including ON-delay, OFF-delay, pulse shaping, and retriggerable modes on one device
  • Standard 35 mm DIN rail mounting in an IP20-rated enclosed panel is your installation environment
  • Electrical endurance of 100,000 cycles at AC-15 matches your expected switching frequency and service interval

If your system runs on a fixed 24 V supply and tighter tolerance is a priority, the 3RP2525-1BB30 is the purpose-matched alternative with a 150 ms recovery time versus 250 ms on this model. If you need more than 2 relay contacts or a semiconductor output, step up within the SIRIUS 3RP25 family accordingly.

On this page:

What the 3RP2505-1BW30 Actually Does in a Control System

The 3RP2505-1BW30 is an electronic multifunction timing relay from Siemens' SIRIUS control product family. Its job is to insert precise, adjustable time delays between a control signal arriving and a downstream load switching — or between a signal releasing and a load de-energizing. Unlike a fixed-function timing relay that handles only ON-delay or OFF-delay, this model stores 27 switching function modes that a technician selects by dial. The result is one stocked SKU that replaces what would otherwise be several separate relay types on a panel builder's shelf.

The relay sits between the control logic layer and the load switching layer of a panel. It receives a control voltage signal at its input terminals, runs its internal timer according to the selected function and dialed time range, then switches its two changeover contacts to activate or release the downstream load. There is no PLC required — the 3RP2505-1BW30 provides standalone timing logic for applications where a full programmable controller is neither justified nor desired. The wide 12-240 V AC/DC input range means it accepts whatever control transformer voltage is already present in the panel, which eliminates a common sourcing headache on retrofit projects.

Proof points worth noting: the SIRIUS mechanical service life is rated at 10 million cycles, and AC-15 electrical endurance reaches 100,000 cycles at 230 V. For moderate-duty applications — pump starters, conveyor sequencers, fan rundown timers — that translates to years of reliable operation before the first planned replacement.

Typical System Architecture for SIRIUS Timing Relays

The 3RP2505-1BW30 sits between the control signal source and the load contactor or solenoid coil, acting as the timed switching bridge that the control logic alone cannot provide. A typical deployment chain looks like this:

  • Control transformer or 24 V power supply feeds A1/A2 supply terminals on the relay
  • PLC digital output, pushbutton, or auxiliary contact feeds the K timing input terminal to start the timer
  • 3RP2505-1BW30 runs its internal timer according to the selected function and time dial setting
  • Changeover contacts (terminals 11/12/14 and 21/22/24) switch the coil circuit of a downstream motor contactor, valve solenoid, or alarm relay
  • Downstream device activates the mechanical or process load — motor, pump, conveyor drive, fan, or alarm horn

Real-World Applications and Deployment Scenarios

Pump startup sequences are among the most common deployments for this relay. A motor soft-start requires a 2-5 second delay before full system pressure is applied, reducing mechanical shock on pipework and seals. The 3RP2505-1BW30 handles this with a straightforward ON-delay function dialed into the 0.5-5 second range.

Conveyor belt systems with multiple belts running in sequence need staggered start intervals — typically 1 to 10 seconds between belt activations — to prevent product pileup at transfer points and to manage inrush current staggering on the supply. One relay per belt stage handles this cleanly without PLC ladder logic changes.

Machine dwell or soak timers for heated tanks and curing chambers require holding a process at temperature for 30 seconds to 10 minutes. The 0.5-5 minute and 5-50 minute ranges on this model cover both bands with the same hardware.

Fan rundown delays in HVAC systems keep fans running for 5-30 seconds after a motor command-off to dissipate residual heat from ductwork. An OFF-delay function on the 5-50 second range handles this directly. Alarm reset logic — where an emergency stop event must latch off power for 3 seconds before allowing manual reset to prevent contact chatter — is another well-matched application.

Application Typical Deployment
Pump startup anti-shock delay ON-delay function, 0.5-5 s range, motor soft-start panel
Conveyor belt sequencing ON-delay per stage, 0.5-5 s or 5-50 s range, multi-belt transfer systems
Machine dwell / soak timer ON-delay or pulse function, 0.5-5 min or 5-50 min range, heated process tanks
Fan rundown delay (HVAC) OFF-delay function, 5-50 s range, air handling unit panels
Alarm reset logic / relay latch Pulse-delay or ON-delay, 0.05-0.5 s or 0.5-5 s range, emergency stop circuits
Wastewater treatment pump cycling Retriggerable function, 5-50 min or 0.5-100 h range, lift station controls

Purchase-Decision Specs and Variant Comparison

Parameter Rating
Control Supply Voltage 12-240 V AC/DC, 50/60 Hz
Voltage Operating Range 0.8 to 1.1 x rated voltage
Output Contacts 2 changeover (CO) contacts
Thermal Current Rating 5 A per contact
Electrical Endurance (AC-15 at 230 V) 100,000 cycles
Mechanical Service Life 10,000,000 cycles
Adjustable Time Range 0.05 s to 100 h (7 discrete ranges)
Switching Functions 27
Recovery Time (typical) 250 ms
Operating Temperature -25 to +60 degrees Celsius

Full technical specifications are available on the product page at LeadTime.ca.

Specification 3RP2505-1BW30 3RP2525-1BB30
Supply Voltage 12-240 V AC/DC 24 V AC/DC fixed
Time Range 0.05 s to 100 h 0.05 s to 100 h
Changeover Contacts 2 2
Switching Functions 27 27
Electrical Endurance (AC-15) 100,000 cycles 100,000 cycles
Mechanical Life 10,000,000 cycles 10,000,000 cycles
Recovery Time (typical) 250 ms 150 ms
Minimum ON Period (typical) 35 ms 35 ms
Best For Mixed voltage systems, universal panels Fixed 24 V systems, tighter recovery needs

If your panel runs a mixed control voltage or you are replacing an existing relay without full knowledge of the original supply voltage, the 3RP2505-1BW30 is the lower-risk choice. If your architecture is fixed 24 V and recovery time matters, the 3RP2525-1BB30 is the correct specification — check current availability of the 3RP2505-1BW30 at LeadTime.ca and contact us to confirm the 3RP2525-1BB30 as an alternative if needed.

Expert Verdict: Honest Assessment and Procurement Reality

The 3RP2505-1BW30 earns its place as a default-spec timing relay for panels that see mixed control voltages or where a single relay needs to flex across multiple function types without re-ordering. The 27 switching functions are a genuine differentiator — most economy timing relays offer 8-12 functions at best, which forces engineers to either change the relay or add external logic. The SIRIUS platform's 10 million mechanical cycle life and 100,000 AC-15 electrical endurance cycles are credible, established figures, not marketing estimates. For moderate-duty applications in manufacturing, HVAC, food and beverage, or wastewater control, this relay will complete a typical service interval without surprises. The wide 12-240 V input range is particularly valuable on retrofit projects where the original panel transformer voltage is uncertain — it simply works across the range without adjustment.

Where this model has real limits: if your application demands a recovery time faster than 250 ms between successive timing cycles, the 3RP2525-1BB30's 150 ms recovery is meaningfully better. If you need more than 2 relay contacts or require a semiconductor output to avoid contact wear on high-frequency switching loads, you are looking at the wrong model. The 5 A thermal current limit also means this relay is switching contactor coil circuits, not directly driving motors or heavy inductive loads — any application where downstream coil current approaches or exceeds 5 A needs an intermediate contactor stage. And IP20 protection is appropriate only inside an enclosed, dry panel; this is not an outdoor or wash-down environment device.

On the procurement side, the 3RP2505-1BW30 is a current SIRIUS family product with established distribution. Standard stock availability at authorized distributors is normal, with typical lead times in the 1-3 business day range for this variant. Volume orders or special configurations may extend to 2-4 weeks; verifying with your distributor before committing a build schedule is always advisable. If you are stocking a spare for a critical timing application, ordering one unit alongside the first installation is straightforward at this price tier. View current stock and pricing for the 3RP2505-1BW30 at LeadTime.ca.

For volume pricing, lead time confirmation before committing to a build, or to discuss the 3RP2525-1BB30 as an alternative, contact the LeadTime.ca team directly — we ship worldwide.

Wiring and Installation Overview

The following points cover the key requirements and configurations engineers need to know before installation. Full step-by-step wiring procedures are available in the Siemens SIRIUS 3RP25 series datasheet and operating instructions.

  • Mount on a standard 35 mm DIN rail using the snap-on method; the relay accepts any mounting position (horizontal or vertical) without affecting function
  • Connect control supply voltage (12-240 V AC/DC) to A1 and A2 input terminals using the removable screw terminals; conductor cross-section must be within 0.5 to 1.5 mm squared solid or stranded wire
  • Connect the timing input control signal to the K terminal — the specific K terminal assignment is function-dependent and must be verified against the wiring diagram for the selected switching function
  • Connect downstream load circuits to the changeover contact terminals (11/12/14 for the first contact, 21/22/24 for the second); install a mandatory external 4 A gL/gG fuse in series with the load circuit before energizing
  • After applying supply voltage, verify the LED indicator illuminates, then test with a low-level control signal before connecting to the actual load; set the time range selector first, then dial the fine adjustment to the desired delay value

27 Switching Functions: What Engineers Actually Use

The 3RP2505-1BW30 provides 27 switching functions accessible by selector dial — no programming required, no software tool needed. Understanding the most commonly used categories helps engineers confirm fit before ordering.

ON-delay is the most frequently specified function: the output activates after the dialed time elapses from when the control signal is applied. OFF-delay does the reverse — the output stays active for the dialed time after the control signal is released, which is the correct function for fan rundown and motor coast-down applications. Combined ON-delay/OFF-delay applies independent start and stop timing to the same relay, useful for machine cycle control where both transition delays matter.

Pulse-delay generates a fixed-width output pulse after a set time delay, while pulse-shaping creates a short pulse from a longer input signal — both are used in alarm sequencing and PLC handshake circuits. The retriggerable function resets the internal timer each time a new input signal arrives before the current timing cycle expires, which is the correct choice for watchdog-style logic where continuous presence of a heartbeat signal is required to hold an output active.

Relative setting accuracy across all 27 functions is plus or minus 5 percent of full-scale value for the selected range. Thermal compensation is automatic at 1 percent per degree Celsius, and supply voltage influence is held to 1 percent per percent of voltage change — both without manual adjustment.

What Engineers Get Wrong When Ordering This Part

The 3RP2505-1BW30 is one of several closely related SIRIUS timing relay variants. Ordering the wrong model is a common delay-causing mistake. Verify every item below before placing your order:

  1. Confirm control supply voltage is truly 12-240 V AC/DC rated, not a fixed 24 V system requiring 3RP2525 dedicated 24 V model
  2. Verify that 2 changeover contacts are sufficient and that instantaneous contacts (not delayed) are available as required
  3. Check that 100,000 electrical endurance cycles at AC-15 meets your load-switching frequency and expected service interval
  4. Ensure 5 A thermal current is adequate for the coil current of downstream contactors or solenoids; verify with equipment datasheets
  5. Confirm that the 0.05 s minimum ON period (35 ms typical minimum) is compatible with your fastest timed pulse requirement
  6. Verify that screw-type removable terminals match your wiring gauge and installation preferences (no push-in connector option on this SKU)
  7. Check that IP20 protection class is acceptable for your enclosure type (not IP65 or higher ingress protection)
  8. Confirm mechanical shock resistance (11 g / 15 ms) and vibration resistance (10-55 Hz / 0.35 mm) suit your mounting environment

If you have worked through this checklist and the 3RP2505-1BW30 fits every point, check current pricing and availability at LeadTime.ca. If any item raises a flag, contact the LeadTime.ca team to identify the correct SIRIUS variant before ordering.

Frequently Asked Questions

Can the 3RP2505-1BW30 run on a 24 V DC control system, or does it require AC?

Yes, the 3RP2505-1BW30 accepts both AC and DC supply voltages anywhere in the 12-240 V range at 50/60 Hz. A 24 V DC control supply falls well within this range. However, if your system is exclusively 24 V fixed and you want tighter tolerance with a 150 ms recovery time instead of 250 ms, the 3RP2525-1BB30 is the dedicated 24 V variant in the same SIRIUS family.

What does the 250 ms recovery time mean for high-frequency cycling applications?

Recovery time is the minimum interval the relay requires after completing one timing cycle before it can reliably trigger again. At 250 ms, the 3RP2505-1BW30 cannot be used in applications where successive trigger events arrive faster than that interval. For high-frequency switching loads where sub-250 ms re-triggering is required, this model is not the correct choice — evaluate higher-speed relay designs with recovery times in the 50 ms range.

How do I select the correct time range when there are 7 options?

The 3RP2505-1BW30 provides 7 discrete ranges: 0.05-0.5 s, 0.5-5 s, 5-50 s, 0.05-0.5 min, 0.5-5 min, 5-50 min, and 0.5-100 h. Select the range that places your target delay roughly in the middle third of the range dial for best accuracy. Setting accuracy is plus or minus 5 percent of full-scale value for the selected range, so a tighter range gives finer practical resolution at your target delay point.

Is the 3RP2505-1BW30 suitable for safety relay functions such as emergency stop monitoring?

No. This model is a standard timing relay and is not certified for safety functions. It must not be used as an emergency stop relay or in any safety-rated circuit. Applications requiring emergency stop, safety category compliance, or IEC 62061/EN 13849 performance levels require a dedicated safety relay. Additionally, this relay requires external short-circuit protection — a mandatory 4 A gL/gG fuse in series with the load circuit.

What wire sizes are compatible with the screw terminals?

The removable screw-type terminals on the 3RP2505-1BW30 accept conductor cross-sections of 0.5 to 1.5 mm squared, either solid or stranded wire. There is no push-in connector option on this SKU. If your installation uses wire gauges outside this range or requires push-in terminals, verify alternative SIRIUS connection accessories before ordering.

How long should I expect this relay to last in a moderate-duty pump control application?

Mechanical service life is rated at 10,000,000 cycles with no external load, and AC-15 electrical endurance is 100,000 cycles at 230 V with an inductive load. In a pump control application cycling several times per day, electrical endurance is typically the binding constraint. At 10 cycles per day, 100,000 cycles projects to approximately 27 years — at 100 cycles per day, approximately 2.7 years. Actual life depends on load type, ambient temperature, and switching frequency; plan replacement intervals based on your specific duty cycle.

Why Order from LeadTime.ca

  • LeadTime.ca ships worldwide — no regional restrictions on orders for SIRIUS timing relays or any other industrial automation products
  • Authorized access to Siemens industrial product lines including the full SIRIUS 3RP25 family with exact SKU verification before shipment
  • Volume pricing available on multi-unit orders — contact the team before placing large build orders to confirm current lead times and pricing tiers
  • Fast response from technical staff who can confirm model compatibility, identify the correct variant, and flag potential wrong-part issues before an order ships
  • Hard-to-find and current-production parts both sourced — useful for retrofit projects where older SIRIUS variants need cross-referencing

At-a-Glance Summary

  • Model: Siemens 3RP2505-1BW30 — SIRIUS multifunction timing relay, screw terminal, LED indicator
  • Control supply: 12-240 V AC/DC at 50/60 Hz; operating range 0.8 to 1.1 x rated voltage
  • Outputs: 2 changeover contacts at 5 A thermal current, AC-15 rated
  • Time ranges: 7 discrete ranges from 0.05 seconds to 100 hours; accuracy plus or minus 5 percent of full-scale
  • Switching functions: 27, including ON-delay, OFF-delay, pulse-delay, pulse-shaping, retriggerable, and combined functions
  • Minimum ON period: 35 ms typical; recovery time: 250 ms typical
  • Mechanical life: 10,000,000 cycles; electrical endurance: 100,000 cycles at AC-15, 230 V
  • Operating temperature: -25 to +60 degrees Celsius; storage: -40 to +85 degrees Celsius
  • Mounting: standard 35 mm DIN rail, any position, IP20 protection class
  • Terminal type: removable screw-type, 0.5 to 1.5 mm squared conductor; no push-in option on this SKU
  • External protection required: mandatory 4 A gL/gG fuse in series with load circuit
  • Not a safety relay — do not use in emergency stop or safety-rated circuits