GTH-220 Three phase Electronic Overload Relays for Motor Contactor

UKH series thermal overload relays apply to circuit of AC 50Hz or  60Hz, rated voltage to below 660V and rated current . 1A-800A for AC motor overload and open-phase protection during long time or intermittent long time service, which can also protect 3-phase serious imbalance and long starting time of motor or long timer operation, can also be used for corresponding AC contactor for electromagnetic starter.

Applications:

Thermal overload relays are designed to prevent damage or destruction of electrical machinery by reacting to increases in current induced temperatures. Should the temperature rise above the rating of the relay, it will activate and disconnect the primary supply and prevent equipment damage. This deactivation is achieved via either a mechanical or electrical interlock between the relay and the main power supply. The temperature sensitive component of a thermal overload relay may be a simple bi-metal strip or a more sophisticated electronic sensor or probe.

Motion Characteristic:

Three phase Balance Motion Time

Phase-losing Motion Characteristic

Construction of Thermal Relay:

The construction of thermal relay is quite simple. As shown in the figure above the bimetallic strip has two metals – metal A and metal B. Metal A has lower coefficient of expansion and metal – B has higher coefficient of expansion. One heating coil is would on the bimetallic strip. When over current flows through the heating coil, it heats up the bimetallic strip.

Due to the heat generated by the coil, both of the metals are expanded. But expansion of metal B is more than expansion of metal A. Due to this dissimilar expansion the bimetallic strip will bend towards metal A as shown in the figure below.

Main benefits:

1.  Reliable protection for motors

2.  Easy to create starters

3.  Optimized match to UKC1 series contactors

4.  Single mounting kits and wire reset for remote control available for specific applications.

Working conditions:

1. The installation altitude less than 2000m

2. The surrounding temperature range: from -5°C ~ +40°C

3. In the non-explosive condition. or without adequate erosion and destruction of gas and

   dust conductive area .

4. Without  rain and snow invade 

5. Pollution level 2