CLIP

CLiP® (Current Limiting Protector) has provided unparalleled system protection, around the world, for over  25 years. It offers the advantages of current limitation for systems rated to 38kV with high continuous current ratings up to 5000A. Fault interruption beyond 300kA rms symmetrical at 15.5kV has been achieved.

With the ever-increasing demand for electrical energy, distribution systems have been forced to expand and grow. Stiffened transmission systems, increased substation capacity, onsite and distributed generation all contribute to subsequent increases in available fault currents imposed on equipment. This short circuit current may exceed its thermal, mechanical and interrupt capability, potentially causing a catastrophic failure. The CLiP is a tool to prevent this.

Current limitation is a key benefit because it yields a significant reduction in the magnitude of the peak let-thru current. Also, since electromechanical forces and fault energy are related to the mathematical square of the current value, limitation of the peak current has a dramatic affect. This can lead to substantial savings by reducing damage, and may also prevent the catastrophic failure of oil filled equipment, or greatly limit arc flash exposure.

Traditionally, the current limiting fuse has provided good overcurrent protection on systems with normal continuous currents up to a few hundred amperes. Their current limitation capability, speed of operation, compact size and low cost make them ideal solutions for certain applications . Expulsion fuses also fill a need. Yet, while these devices are relatively fast acting, they are unable to limit the destructive forces related to the peak currents. Electromagnetic forces and fault energy are related to the square of these unlimited peak current values.

For higher continuous currents, circuit breakers are most commonly used. However, circuit breakers are not current limiting and are relatively slow interrupting devices (3-5 cycles). The application of a CLiP for protection of  under-rated circuit breakers can provide significantly improved protection at a substantial cost savings over replacement of those circuit breakers. For applications where available fault currents have increased due to expanding power requirements, simply replacing the circuit breakers may not be adequate protection for other under-rated equipment on the system.

Another device is the current limiting reactor. Reactors have high continuous current capabilities and are current limiting. However, they require an auxiliary device to do the actual fault interruption. Reactors are inherently costly to operate because they introduce substantial losses to the system and impose an undesirable regulating voltage.

CLiP is the successful result of a project sponsored by the Electric Power Research Institute (EPRI), to develop a cost effective, single-shot, high continuous current, medium voltage current limiter for use indoors or out. These are five highly desirable elements never before available in one overcurrent protection device.

Current Limiting Protectors (CLiP®) can offer the advantages of current limitation for 2.8 through 38 kV systems with continuous current ratings up to 5000 A. Compact, totally sealed construction permits the CLiP to be installed both indoors and out, either pole or structure mounted or within an enclosure.

The CLiP’s unique ability to provide high continuous current ratings with current limitation and ultra-high speed of operation in one package make it an economical solution for a variety of overcurrent protection needs including:

 Save money – Upgrade the system source by adding transformers or co-generators (resulting in higher available fault currents) without the changeout of downstream breakers.

– Bypass current limiting reactors to eliminate regulating voltage drop and real operating cost (up to tens of thousands of dollars per year) and eliminate voltage regulation difficulties.

– Close tie position breakers to improve voltage regulation or avoid further system upgrades while still being fully protected.

– Protect under-rated equipment (the ones that have been neglected over the years) and satisfy your insurance companies.

– Reduce Arc Flash Exposure Protective suits will only help with the thermal effects and not with the concussion. The CLiP can greatly reduce fault energy for much improved personnel protection.

– Protect the system from additional fault backfeed of large rotating loads.

– Reduce fault energy to limit damage or prevent transformer tank rupture (let-thru I2t is commonly 0.5% of that from a 5-cycle breaker).

– Clear the generator with high asymmetries in 1/4 cycle where the breaker may not reach an effective current-zero for many cycles.

– Limit cogenerator fault contribution to the utility within utility mandated limits.

– Protect cogenerators – it’s a multimillion dollar investment that a breaker alone cannot fully protect. 5.5kV, 3000A CLiPs protecting the utility from a small cogeneration plant. Structure mounted 38kV, 1200A CLiPs in a reactor bypass application.

– Escape the cost of full rated breakers (especially generator breakers) and have a more effective protection package. Let the CLiP handle the excessive faults.

– Protect capacitor bank switches by limiting fault currents without operating on energization inrushes.

– Protect harmonic filter systems without responding to the higher frequencies and associated di/dt.

– Bypass neutral reactors to maintain system balance until a major fault occurs.

– Limit damage from singlephasing and ferroresonance by causing three phase clearing.

– Limit fault damage to variable speed drives.

– Improve power quality by limiting the fault contribution to adjacent faulted buses that would cause unacceptable voltage sag on the system.

– Protect wind turbine systems from excessive grid fault energy and the grid from additional fault contributions.

– Reduce potential flying debris in busy metro areas (e.g. manhole covers) resulting from network or other underground system faults. The CLiP can effectively limit fault energy.

Have a special application outside of our published ratings? Call us. We will work with you to provide a solution.