Automatic Inverse Time Protective Relays IDMT Overcurrent Protection

Time overcurrent relays operate with a time delay, which is adjustable. For given setting, the actual time delay depends on the current through the relay coil. Higher current will cause a faster operation of the relay. The minimum relay operation current (pick-up current) is also adjustable.

The most commonly used overcurrent relay has both the instantaneous response for very large currents and the inverse time response for lower currents. A relay  is intended protect loads or circuits from excessive current.

Description:

KRIPAL overcurrent protection delivers comprehensive protection schemes for low voltage applications. All Mikro's overcurrent units are microprocessor-based numerical relays and are housed in high-strength protective casing. The models in the range provide a wealth of options including programmable relay outputs to static, and digital display or dial activated..

FEATURES 

A. Low-set inverse definite minimum time relay 
B. High-set instantaneous 
C. Separate low-set and high-set trip indicators 
D. Trip starting indication 

Specifications:

SETTING RANGES 
Low-set: 2A to 6A; 40% to 120% 
Time multiplier: 0.01 to 1.0 
IDMT curve: Normal inverse 
High-set(l>>): i> to 5× l> 

CONTACTS 
Trip contact: Automatic reset type 
Contact rating: NC NO contact type 
                        6A. 250V AC 
                        Silver alloy contact material 
                        100, 000 electrical operations at rated currents 

IINDICATORS 
Trip indicator: Manual reset type 

PERFORMANCE 
Adjustable accuracy: Less than ± 5% 
Repeatability: Less than 0.5% of full scale

Benefit:

• Accurate, reliable and more resistant to vibration and shock than traditional electromechanical relays
• Current measurement based on fundamental frequency, prevents nuisance tripping
• Digital display or dial activated for ease of use
• Robust casing protects the unit from external interference
• Complies with IEC 60255-26 standards

Applications:

Feeder incoming protection
Outgoing protection
Busbar protection

Full series: earth leakage relay, earth fault relay, overcurrent relay, zero phase transformer