SIEMENS RAK-TW.5010S-H Protection Thermostat

Vollständiges Modell: RAK-TW.5010S-H

Bestell-Nr.: S55700-P122

Marke: SIEMENS (Building HVAC Series)

Produkttyp: Capillary frost protection thermostat (TW frost-type temperature limit switch)

Core Contact: SPDT single-pole double-throw switching contact

Herkunft: Original imported from Switzerland/Germany

Compatible Power Supply: Wide voltage range AC 24V ~ AC 250V

2. Segment-by-Segment Model Code Breakdown
3. RAK: General prefix for full series of mechanical capillary temperature switches
4. TW: Type Winter Frost, dedicated thermostat for frost protection (low-temperature anti-freeze logic)
5. 5010: Temperature measuring range code `-10℃ ~ +50℃`

First two digits 50: Upper limit 50℃

Last two digits 10: Lower limit -10℃

4. S: Sleeve-free, no immersion temperature sleeve, fixed only by binding capillary
5. H: Standard housing with push-in quick-disconnect terminals

Supplementary coding rules for the same series:

B = Equipped with immersion temperature sleeve

M = With external adjustment knob

TR = High temperature limit type

ST = Overheat protection thermostat

3. Terminal Wiring & Contact Logic

Terminaldefinition (SPDT Switching Contact)

Gemeinsames Terminal 1, normally closed circuit 1-3, normally open circuit 1-2

1. Frost Protection Action Logic (Triggered by Temperature Drop)

When medium temperature drops to the set frost protection value → contacts switch: Schaltung 1-3 disconnects, Schaltung 1-2 closes, activating heat tracing/circulating pump anti-freeze circuit.

2. Reset Logic (Recovered by Temperature Rise)

When temperature rises by a fixed hysteresis of 5K → contacts automatically switch back to 1-3, and the anti-freeze circuit shuts down.

Contact Load Capacity (Wechselstrom 250 V)

Schaltung 1-2 (Frost protection output): 16(2.5)A

Schaltung 1-3 (Normal state signal): 6(2.5)A

Terminal structure: Tool-free push-in wiring, suitable for 0.5~2.5mm² solid and flexible wires.

4. Kernelektrik & Mechanische Parameter
5. Adjustable Temperature Range: -10℃ ~ +50℃
6. Switch Hysteresis: Fixed 5K (5℃), nicht verstellbar
7. Capillary Length: Standard 1600mm liquid expansion temperature-sensing capillary
8. Schutzklasse: IP43 housing, UV-resistant flame-retardant plastic shell
9. Three-in-One Mounting Method: Pipe strap mounting / duct sleeve mounting / wall mounting
10. Mechanische Lebensdauer: ≥ 100,000 switching cycles
11. Ambient Operating Temperature: -20℃ ~ +60℃
12. Abmessungen: 156×72×55mm; Net weight ≈ 320g
13. Compliance-Standards: CE, RoHS, DIN EN 14597 safety standard for HVAC thermostats
14. Funktionen & Anwendungsszenarien

Kernfunktion

Provides low-temperature frost protection for pipes and air ducts. Automatically activates anti-freeze heat tracing and circulating pumps when medium temperature is too low to prevent water pipe cracking; meanwhile, low-temperature alarm signals can be uploaded to PLC.

Segmented Application Fields

1. Central Air Conditioning / Air Duct Systems

Frost monitoring for chilled water pipes and fresh air ducts of air conditioners; activate pipe heat tracing cables under low temperature conditions.

2. Heizung & Hot Water Boiler Rooms

Frost protection for plate heat exchangers, water manifolds and outdoor main heating pipelines.

3. Building Electromechanical BA Systems

Low-temperature alarm for chillers, cooling tower makeup water pipes and plumbing pipes in underground parking lots.

4. Purification / Pharmaceutical HVAC Systems

Anti-freeze interlock for circulating water pipes and process air ducts in clean workshops.

5. Cold Chain Supporting & Computer Room Air Conditioning

Frost monitoring for pipelines of outdoor water-cooled units and precision air conditioning water pipes in equipment rooms.

6. Heating Pipe Networks in Industrial Workshops

Anti-freeze protection for workshop circulating hot water pipes during winter shutdown.

6. Selection Table for RAK-TW Frost Protection Series

7. Ersatz & Cross-Brand Substitution Instructions

7.1 Direct Substitutes from Siemens Same Series

For water tank immersion application: RAK-TW.5010B-H (only equipped with extra temperature sleeve, identical temperature range and contacts)

For high-temperature overheat protection only: Switch to RAK-TW.1000 series (temperature range 15~95℃)

7.2 Cross-Brand Substitutes with Identical Functions

Danfoss: 060G3450 frost capillary thermostat

Johnson Controls: A11B-4C frost limit switch

Inländische Alternative: Shanghai Fengshen WTQ series capillary frost thermostat

7.3 Notes on Replacement

1. Only TW frost type (triggered by temperature drop) verwendet werden kann; TR overheat thermostats (act on temperature rise with opposite logic) are prohibited.
2. The capillary length of the substitute should match 1600mm as much as possible to avoid temperature measurement delay.
3. The built-in contact is SPDT switching type; it cannot be directly replaced by thermostats with single NO or single NC contacts.
4. Strict Usage Prohibitions
5. Do not apply to steam or oil media over 50℃ (exceeding the range will permanently damage the capillary).
6. The capillary must not be sharply bent or squeezed; minimum bending radius ≥50mm, otherwise temperature measurement will fail.
7. IP43 rating is only applicable to indoor or covered outdoor environments; long-term exposure to open rain is forbidden.
8. Contacts are only for AC24~250V control circuits; connection to 380V main power circuits is prohibited.
9. Do not cut the capillary; length modification will deviate the calibrated temperature measurement accuracy.

Replacement Instructions for Temperature-Sensing Probe (Capillary Bulb) of SIEMENS RAK-TW.5010S-H

1. Kernschlussfolgerung

The temperature-sensing probe/capillary cannot be replaced separately by original parts. The temperature bulb, capillary and internal bellows actuator form a sealed integrated welded assembly which cannot be disassembled for replacement.

1. The capillary and thermostat body are filled with special expansion liquid and hermetically welded. Disassembly will cause liquid leakage and permanent scrapping.
2. Siemens does not sell separate spare capillary probes of 1600mm specification, and split spare parts are unavailable.
3. Once the probe is bent, squeezed, leaked or broken, the only compliant solution is to replace the whole unit with RAK-TW.5010S-H.
4. Structural Principle (Why the Probe Cannot Be Replaced Separately)
5. Working medium: The temperature bulb and capillary are hermetically filled with liquid of high expansion coefficient, which drives the internal micro-switch via thermal expansion and contraction.
6. Connection process: The root of the capillary and internal bellows of the housing are integrally brazed and sealed without detachable joints.
7. Calibration matching: The 1600mm capillary length, bulb volume and liquid filling volume are uniformly calibrated at factory. Arbitrary probe replacement or capillary length modification will lead to:

Severe shift of operating temperature and out-of-control hysteresis;

Failure of low-temperature anti-freeze logic and risk of pipe cracking;

Non-compliance with DIN EN 14597 HVAC safety thermostat certification and unqualified equipment acceptance.

3. Fehlerurteil & Lösungen

3.1 Typical Symptoms of Damaged Probe

Capillary bent and flattened, pipe wall broken with liquid leakage;

Temperature bulb dented or fractured by impact;

Thermostat stays unswitched for a long time with no response via temperature adjustment window;

Operating temperature deviation exceeds ±5℃ and adjustment is invalid.

3.2 Handling Methods

1. For formal projects requiring acceptance: Purchase a brand-new complete RAK-TW.5010S-H unit for direct replacement.
2. Temporary emergency use (no acceptance requirement, long-term use not recommended): Do not cut or splice the capillary; only bind the intact segment temporarily for temperature measurement with unguaranteed accuracy.
3. Complete Substitute Units of the Same Specification (No Mounting Modification Required)
4. Direct replacement with original identical model: RAK-TW.5010S-H (Bestell-Nr. S55700-P122, 1600mm capillary without sleeve)
5. For water tank immersion application: RAK-TW.5010B-H (identical temperature range, matched temperature sleeve and fully consistent other parameters)
6. Installation & Usage Restrictions (To Avoid Probe Damage)
7. Minimum bending radius of capillary ≥50mm; sharp right-angle bending, treading and squeezing are forbidden.
8. Cutting, truncating and splicing of the capillary are strictly prohibited.
9. The temperature bulb can only contact media ≤50℃; contact with high-temperature heat sources or welding slag is forbidden.
10. Avoid sharp metal clamps scratching the outer wall of the capillary during pipe binding.
11. Do not pull the capillary hard during transportation; leave loose allowance.
12. Alternative Cross-Brand Complete Units

If the delivery cycle of Siemens products is long, replace with complete frost capillary thermostats of identical logic:

Danfoss 060G3450 (-10~50℃, 1.6m capillary SPDT frost switch)

Johnson Controls A11B-4C low-temperature frost limit switch