Description
3-phase thermal overload relay for overcurrent and phase-failure protection. It is used to provide overload protection open-phase protection and protection against unbalanced current for motors and it can also avoid heating in electrical equipment. Current setting range 10~18 Amps, rated working current 25A, voltage 220V~690V. Low price thermal relay is matched with 9A contactor, 4~20A gG fuse breaker.
Specification
| Model | ATO-JR28-25 | ||||
| Current Setting Range (A) | 5.5-8 | 7-10 | 9-13 | 12-18 | |
| Matching Fuse Breaker (A) | gG | 20 | 20 | 25 | 35 |
| aM | 12 | 12 | 16 | 20 | |
| Trip Class | 9A | ||||
| Frame Current (A) | 25A | ||||
| Rated Working Voltage (V) | 3-phase 220V~690V | ||||
| Rated Insulation Voltage (V) | 690V | ||||
| Number of Contacts | 1NO + 1NC | ||||
| Phase Failure Protection Function | yes | ||||
| Automatic & Manual Reset | yes | ||||
| Temperature Compensation | yes | ||||
| Tripping Indicator | yes | ||||
| Test Pushbutton | yes | ||||
| Mounting Mode | Plug-in, independent | ||||
| AC-15 220V Current Rating (A) | 2.73 | ||||
| AC-15 220V Current Rating (A) | 1.58 | ||||
| DC-13 220V Current Rating (A) | 0.2 |
Details
Thermal Overload Relay Applications
- Thermal overload relays are often used in circuit protection, overload, phase failure, overtime start and locked-rotor for AC motors.
- Thermal overload relay has functions of phase failure protection, temperature compensation, adjustable setting current, automatic or manual reset, operation indicator, NP and NO auxiliary contacts separate insulation.
- The thermal overload relay has small installation area and various mounting methods. It has test button and stop button, which is convenient for checking the flexibility of operation.
- The protective cover of thermal overload relay can protect fingers from electric shock. The locking device can prevent misoperation.
- Thermal overload relay comes with remote operation, complete functions and excellent quality.
10~18 Amp Thermal Overload Relay Dimension Diagram (Unit: mm)
Cross Section Area of Conductor
| Main Circuit | Single core or standard wire | 1~4 mm2 |
| Wiring screw | M4 | |
| Auxiliary Circuit | Single core or standard wire | 0.5~2.5 mm2 |
| Wiring screw | M3.5 |
Tips: 10A thermal overload relay working principle and functions.
Thermal element of the 10A thermal overload relay is connected to the AC motor circuit directly or through a current transformer. When AC motor is overloaded, the main bimetal is heated to the operating temperature, then relay is activated, and the power circuit of motor is disconnected to prevent the AC motor from being damaged by overload.
The action time of 10A thermal overload relay and the magnitude of overload current change according to the inverse time limit. Therefore, its thermal characteristics are easily matched with the thermal characteristics of AC motors. In addition, 10A thermal overload relay has the features of compact structure, low price, stable action performance, and convenient use. Therefore, since the 1990s, most squirrel-cage rotor motors and some wound-rotor motors still use 3-phase thermal overload relays as protections for overload, phase failure, and current unbalanced operation. 10A thermal overload relay can also be used as a control appliance for the heating state of other electrical equipment.
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