Siemens 3RU21161AB0 Thermal Overload Relay
Catalog Identity and Parameter Summary
The Siemens 3RU21161AB0 is a thermal overload relay in the SIRIUS 3RU2 series, designated size S00, with a Class 10 tripping characteristic and an adjustable current range of 1.1–1.6 A.
| Parameter | Value |
|---|---|
| Accessory Type | Thermal Overload Relay |
| Series | SIRIUS 3RU2 |
| Base Product Number | 3RU2116 |
| Size Class | S00 |
| Current Range | 1.1–1.6 A |
| Encapsulation | Bulk |
| For Use With | Contactors |
| RoHS | ROHS3 Compliant |
| Product Status | Active |
The 3RU2116 base number groups a family of size-S00 thermal overload relays that snap onto corresponding SIRIUS contactors. The two-letter suffix before the final digit (AB in this case) encodes the current-class variant. The CL10 designation indicates that the relay will trip within 10 seconds at approximately 7.2 times the set current—a standard protection class for motor loads.
S00 Frame Integration
All 3RU2 size-S00 overload relays share the same physical footprint and mount to the same contactor frame. They provide motor-branch overload protection by sensing heater-element temperature rise through a thermal bimetal mechanism. When the primary MPN is evaluated for a given motor feeder, the current-setting dial must be set to match the motor nameplate full-load current.
The bulk encapsulation variant ships without retail packaging, which is typical for panel-builder stock replenishment. The relay is listed as compatible with contactors, confirming its role as a downstream accessory in a motor-starter assembly.
Current-Class Comparison Across 3RU2116 Family
The in-catalog alternates share the same series, base number, accessory type, encapsulation, and contactor compatibility. They differ in the current-setting range assigned by the factory calibration class.
| MPN | Current Range | Stock (units) |
|---|---|---|
| 3RU21161AB0 | 1.1–1.6 A | 4 |
| 3RU21161BB0 | 1.4–2 A | 4 |
| 3RU21161CB0 | 1.8–2.5 A | 4 |
| 3RU21161DB0 | 2.2–3.2 A | 5 |
| 3RU21161EB0 | 2.8–4 A | 10 |
| 3RU21161FB0 | 3.5–5 A | 5 |
| 3RU21161GB0 | 4.5–6.3 A | 3 |
| 3RU21161HB0 | 5.5–8 A | 21 |
| 3RU21161JB0 | 7–10 A | 8 |
These parts require the designer's own selection verification against the specific motor full-load current and starting conditions.
Selecting a 3RU2116 Current Class
- Match the motor nameplate FLA to a setting range that places full-load current near the middle of the dial.
- Class 10 relays suit general-purpose induction motor protection; verify that starting current and locked-rotor time are within the Class 10 trip curve for the selected motor.
- Adjacent current classes (AB, BB, CB, DB) form a near-continuous coverage chain from 1.1 A to 3.2 A; where a motor's FLA falls between calibration midpoints, the next higher class may be acceptable if the dial can be set within 20–25 % of actual FLA.