Triplen Filter is the ultimate switching voltage Surge Protection Device

Unlike SPD or TVSS, it extinguishes switching transient voltage surge, over or under the operational voltage, besides diverts current surge, balances 3ph power and eliminates neutral current. It effectively and optimally provides online power-frequency voltage surge protection for all equipment within a power system, be it at raw power or UPS output power.  It protects sensitive electronics and electrical equipment 24/7 from continuous and repetitive operating voltage fluctuations which may originate in the grid or inside within a factory.

Switching voltage surge suppressor is a functional protection device, protecting your equipment, always. It gets rid of voltage fluctuation instantly whenever it spikes higher (voltage swell) or dips lower (voltage sag) from its instant working voltage level. It's a stabilization tool that mitigates momentary rise and fall in both voltage and current spikes. It also reduces both transient and steady-state neutral current and neutral voltage by up to 90%.

Whereas, Surge Protection Device (SPD) is a standby protection device. It better serves as insurance against a future lightning strike. It cuts off excessive-high voltage from a lightning impulse voltage. That typically is above twice the operating voltage and lasts for a short time of few microseconds, unlike the power frequency voltage surge, which lasts a thousand time longer and varies from little to several hundred milliseconds.

Triplen Filter (a switching surge protection device) protects against all five Electrical Disturbances. 

1. Grid voltage fluctuation.

2. Abrupt power fluctuations during load switching or line fault, within the plant or outside at utility supply grid.

3. UPS output voltage surge and electronics failure - UPS being a low fault level (high impedance) device causes transient power surge during load switching, and load fluctuations. Besides UPS passes on input voltage spike to output as dc ripples. Triplen filter mitigates electronic failures in the manufacturing process and material handling automation and robot control system.

4. Harmonic voltage disruptions from power lines.

5. High voltage inrush between IGBT Collector and Emitter terminals during turning off due to stray inductance - the active clamping protection using TVS Diode delivers only differential voltage protection.

The IGBT (Insulated Gate Bipolar Transistor) has another disadvantage; to overcome it uses TVS Diode clamping technique. Its gate is of MOSFET structure which is susceptible to Electrostatic Discharge (ESD) and induced over voltage due to the Miller effect. It develops overvoltage while driving the gate using pulse switching signals due to Miller Capacitor.   

Surge Protection Device (SPD) clips high impulse lightning voltage

On the other hand, Surge Protection Device (SPD) also known as Transient Voltage Surge Suppressor (TVSS) or Surge Suppression Equipment (SSE) is a protection device which serves better unutilized and, only as insurance against lightning strike.  A bolt of lightning causes a temporary rise in voltage typically 2000 volts 100 amperes on a low voltage network. On the high voltage power system, it could exceed 50KV on a 1.2/50uS impulse wave for type-1 SPD or Lightning Arrester, and at main LV incomer 10kA on an 8/20uS impulsive wave for type-2 SPD.

The standard IEC 60060-1 and ANSI/IEEE C62.41 define lightning impulse voltage having a rise time T1 of 1.2uS (microsecond) and 50uS as fall time T2 to 50% its peak value. SPD activates when the common-mode dc voltage on the power system exceeds several times its instant working voltage due to lightning, cliffs it off and diverts it into a ground wire within a short time typically 100-microsecond. However, the SPD itself is vulnerable to failure at sustained power frequency over-voltages little over its working voltage which may originate from the power system and prolong typically beyond 100-milliseconds. The Metal Oxide Varistor (MOV) inside SPD degrades gradually on sustained temporary overvoltages (TOV) which slowly break down its resistance from megaohm to milliohm and increase leakage current through the MOV. The resultant heat eventually fails the varistors.

In the solar plant case study, a 100kW Solar power plant installed CITEL make type-2 SPD based on high energy varistors with thermal disconnectors. It has a nominal line voltage Un 230v, max operating voltage L-N Uc 280v, TOV 150% of Un, and Protection voltage Up 1.3kV with discharge current In 20kA. One type-2 SPD installed at the LT incomer switchgear of 250kva transformer and another at the incomer PCC of 100kw solar inverter. Both the SPDs were failing repetitively.

Causes of Electrical Disturbances, Voltage Spike and Volt Sag

Repetitive tripping and failure in sensitive equipment like SMPS power supply, Metal Oxide Varistors MOV, SPD, capacitors, electronics, inverters and drives and plant automation system happen on account of power frequency voltage fluctuations. Wherein voltage sags and swells contribute to the failures. But from where do the voltage fluctuations come?

1. The voltage surges are ordinarily due to a tree falling on an overhead transmission line, which mostly causes single-phase to ground fault but could extend into a phase-to-phase to earth fault under severe weather condition.

2. An insulator blast on overhead transmission-line could cause a single-phase to the ground or a line to line fault. It's recorded in a signature analysis in a separate web page under "effects of a lightning bolt on power system". These kinds of grid faults cause the voltage to dip momentarily on the affected phase(s) which results in an abrupt surge voltage on the unaffected phases.

3. The common causes of power surge originating within a plant are switching on-off of high powered electrical equipment and motors.

4. The other causes of a transient power surge are faulty wiring, electrical noise which is high-frequency current, high harmonics and utility power supply failure.  

How Voltage Surge Suppressor (a surge protection device) eliminates equipment failure

Controlling a transient asymmetric power surge requires magnetically intertwining the 3P4W system's all electrical power wires. Apart from its three phases and neutral being magnetically intertwined, it's a magnetic energy storage device that opposes sudden voltage surge in the unaffected-phases in the event of an asymmetric line to ground or line to line fault. To maintain its ampere turn balance, it raises the transient fall in voltage in the affected phases in proportion. Summarily it stabilizes three-phase and neutral voltage profile of an electrical power system thereby protecting the connected sensitive equipment from unwanted tripping and failures.

Electronics and integrated circuitry are most susceptible to power level overload and degrade overtime on switching surges which produce a brief surge of power across a line every time it gets on and off. This small bits of damage eventually result in the shortening of the lifespan of the equipment. Triplen filter, by its automatic voltage surge suppression capability, protects sensitive electronics from gradual degradation and failure.   

Mitigating tripping and failures of Solar Inverters due to voltage fluctuation

A cashew packaging and cashew-kernel oil extraction plant have 290kW connected load powered through a 250kva, 11kv/433volts transformer.  It installed 100kW solar power plant comprising of 302nos solar panels each generates 330W at 42Vdc no-load voltage or 37Vdc full load voltage. A set number of solar panels connect in series and parallel through a DCDB for obtaining an operating voltage of 1000Vdc no-load or 600Vdc full load for connecting to solar inverters' input which converts DC power into a 3phase AC power and supply to 3P4W, 415V low voltage utility feeder. Each DCDB consists of three incomers totalling 3sets 1000Vdc photovoltaic fuses and a common DC-SPD which is a PV type Surge Protector with maximum operating voltage Uc-PV 1060Vdc and protection voltage Up 3.6Kv with 20kA rated surge current. The solar plant has 4nos solar inverters, 3nos 27.6kW, each of which connects to 84nos solar panels and 1no 17kW which connects to 50nos solar panels. It was facing repetitive failures in AC type-2 SPD, and Solar Edge made Solar Inverters, wherein the PCB capacitors, MOV and pulse transformers were burning. Triplen filter, which is the ultimate Surge Protection Device resolved all problems instantly on installation.