Surge and transients are used in the industry interchangeably. Both are high voltage (110% above the rated voltage) and high current short duration high energy pulses that can cause damage to the sensitive electrical and electronic loads. Surges enter the facility from the outside, such as lighting strikes. In contrast, the transients are generated internally through capacitive switching, starting/stopping loads, fault/arc initiation, power system recovery, etc. 

Switching noise, higher-order harmonics (3-100kHz) is the transient energy generated at the time of load switching. Today’s electronics constantly switch from AC to DC, DC to AC frequently for its operation. During the switching process, the electronics generate an unwanted electrical signal called “switching noise.” The switching noise is often referred to as high-frequency noise or higher-order harmonics throughout the EP literature. 

The three terms mean similarly referring to electrical noise in the range of 3-100kHz

High-frequency noise, 3-100kHz, is the electrical noise resulting from switching transients. The negative consequences of higher-order harmonics are: 

1. They cause premature damage to the equipment 

2. Malfunction and erratic behavior of the electronic equipment 

3. Electrical resonance phenomenon in the power system 

No, the damage may not be instantaneous to the distribution system. The noise constantly alters the capacitive reactance of the load, resulting in erratic behavior, premature damage to the load. 

The surges and transients may cause instantaneous damage to the electrical loads in fire, arc, or permanent damage to the system. The internally generated transients might not damage the load instantly but will affect the performance of the system. 

70-85% of the total transients in a facility are generated internally. The sources of the internally generated transients are: 

1. Load switching 

2. Non-linear load behavior such and VFDs, and PLC 

3. AC-DC power conversion 

4. Starting and stopping loads 

5. Arcing faults (ground) 

6. Discharge of inductive loads such as transformers, motors 

7. Contactors, relays, and circuit breaker operation. 

The rest 15-30% transients are generated outside the facility in high energy surges. The sources of externally generated surges are: 

1. Lightning – both direct and indirect hits 

2. Utility initiated grid and capacitor switching 

No, the traditional SPD installed at the main panel will remove the externally generated noises entering the building. 

EP technology:

1. Uses Thermal based Metal Oxide Varistor for its surge protection device circuitry, complying with UL 1449 3rd Ed to remove externally generated surges and transients.

2. Uses waveform correction and low pass filter circuits to continuously remove the switching noise / higher-order harmonics generating internal to the facility.

Circuit breakers are current-based devices that respond in 5-20 milliseconds. Circuit breakers cannot stop the voltage surge or transients that are usually in microseconds. The SPD in the EP technology is the only device that can protect your facility from surges. 

Yes, the UPS are a great device when power interruptions are expected at the load, but they do not protect your loads from noise and transients. UPS may have inbuilt surge protection but not significant enough to handle the transients generated at the main panel. The facility still needs large kA rated SPD at the main panel and the load center 

Transients and surges may not damage your loads immediately. The transients hitting the electronics loads constantly alter the capacitive nature of the load, resulting in a slow death. The longevity of the load significantly diminishes over a period. The worst part is – the load tends to generate heavy inrush/discharge current before it dies, resulting in damage to other electrical loads in a facility. Ex: Your outdated furnace will take some other electrical loads along with it when it breaks. The facility must need EP units that constantly absorb the noise and filter them out, so the life of your equipment is extended without causing maintenance issues. 

Significant. The lead length of the EP units must be as – short – as possible for effective surge and noise filtration. For every one inch of the wire, an additional 20-25V of let-through voltage is added. The surge and transients are high-frequency noise that has a higher impedance when the wire length is increased. All EP units’ VPR numbers are taken at a 6-inch lead length. 

Not often, the EP filters are robust enough to withstand harsh electrical environments. The LED indicators on the EP units show the active phase. The units need to be immediately replaced if any of the LEDs are off. The units may fail when they are subjected to continuous high surge events. Some of our EP filters are still running well after 20 years of installation. 

No, they do not need maintenance. Clean the surrounds and make sure the LEDs are visible to the operations/facility professionals. 

Yes, EP makes surge protection and noise filters for DC applications. Contact us at info@ep2000.com to find out the unit model number.