Specifications : GENERAL Rated Power 5000VA / 5000W Communication Interface Removable USB / RS232 / RS485 / Bluetooth / Dry-contact Dimension D x W x H (mm) 115 x 300 x 400 Net Weight (kgs) 13 INPUT Voltage 230VAC Selectable Voltage Range 170 ~ 280 VAC (For Personal Computers)90 ~ 280 VAC (For Home Appliances) Frequency Range 50Hz / 60Hz (Auto sensing) OUTPUT AC Voltage Regulation (Batt. Mode) 230VAC ± 5% Surge Power 10000VA Efficiency (Peak) 90% ~ 93% Transfer Time 15 ms (For Personal Computers)20 ms (For Home Appliances) Waveform Pure sine wave BATTERY Battery Voltage 48VDC Floating Charge Voltage 54VDC Overcharge Protection 63VDC SOLAR & AC CHARGER Solar Charger Type MPPT Maximum PV Array Open Circuit Voltage 500VDC Maximum PV Array Power 5000W MPP Range @ Operating Voltage 120VDC~450VDC Maxmum Solar Charge Current 100A Maximum AC Charge Current 100A manufacturer link
Aokly Gel Battery 12V – 200A 58.5Kg manufacturer link
INVO Online INH300 Centralized server center, mainframe, network control center, computing center Full Specifications : 3KVA 2100 W Half -Load 120 -300VAC, Full -Load 165V -300VAC 45.5Hz ~ 54.5Hz 220/230/240V ± 3% Waveform True Sine wave Frequency 50/60Hz ± 0.5 Distortion <3%(linear Load); <5%(Non -linear Load) Crest Factor 3:1 Efficiency 85% Overload Capacity 110%-150%:Switch to Bypass after 1min; >150%:Shutdown afte r 200ms Short Circuit UPS output turn off and alarm RS232 ;SNMP (Optional) LCD & LED Utility, Inverter, Bypass, Battery, Load ,Battery Mode ,Frequency , UPS Fault Indicator Audible Alarm -Battery Discharge Utility Failure, Beep/4s;Battery Low, Beep/1s UPS Abnornmal Continuous Beep and Red Led On Noise <55db (1Meter) Temperature 0°C~40°C Humidity 10%~90% Optional 19 inch Rack -mount Dimension (W * D * H) mm 357 x 144 x 215 439x190x341 514X262X455 (Long Time Mode) 514x262x710 (Standard Model) Specifications: Specifications : INVO Online UPS High Frequency 3000 VA, LCD Display Inbuilt Battery 6 x 12V/7Ah AC Input 2. Bypass 3. AC Output 4. Battery 5. Fault 6. Screen 9. LCD 1. AC Input 2. Bypass 3. AC Output 4. Battery 5. Fault 6. Screen 9. LCD 1 year warranty Manufacturer Link
The Twist Online High Frequency UPS 1KVA TWUP1000/HF delivers stable backup power for servers, networking devices, and office equipment. It uses online double conversion technology for continuous clean power output. Additionally, the high-frequency design improves efficiency and reduces switching interruptions. Moreover, the UPS includes an LCD display for real-time monitoring and system status updates. It also features built-in 2x12V/9Ah batteries for backup operation during outages. Therefore, it protects connected devices from voltage fluctuations, surges, and power loss. Furthermore, the TWUP1000/HF supports pure sine wave output for sensitive electronic equipment. It also includes overload, short-circuit, and overheating protection for safer operation. Additionally, the compact tower design fits home, office, and IT environments easily. Specifications: 1KVA online double conversion UPS technology Built-in 2x12V/9Ah rechargeable batteries LCD display for system monitoring Pure sine wave output for stable power Overload and short-circuit protection system
APC UPS Accessories SRVRK2 APC Easy UPS RAIL KIT, 900MM, 1 – 10KVA (Rackable SRV models)
UPS PCE EXDC-2 MAX UPS Adapter for Cameras & Modems
MARSRIVA SMART MINI DC UPS 10000MAH Capacity: 10000mAh / 37Wh. Output Interface: USB-A Output: 5V at 2.4A, DC Output: 5V / 9V / 12V (selectable) at 1.5A, POE Output: 5V at 2.4A. Dimensions: 104.5 x 170 x 30.8 mm. Net Weight: 360g. Color: Black. Specifications: MARSRIVA SMART MINI DC UPS 10000MAH Capacity: 10000mAh / 37Wh. Output Interface: USB-A Output: 5V at 2.4A, DC Output: 5V / 9V / 12V (selectable) at 1.5A, POE Output: 5V at 2.4A. Dimensions: 104.5 x 170 x 30.8 mm. Net Weight: 360g. Color: White.
The PCE PCD 12V 65Ah Deep Cycle Battery delivers dependable power for a wide range of applications. It provides stable energy over long discharge cycles. This battery supports regular use in marine, RV, solar, and backup power systems. It fits well where lasting performance matters. Moreover, the PCE PCD Deep Cycle Battery features a deep cycle design for long life and strong reliability. It tolerates repeated charging and discharging without damage. This increases uptime and reduces maintenance needs. Users enjoy continuous power without frequent replacements. In addition, the battery delivers 12 V and 65 Ah capacity for steady power delivery. This suits medium and high demand systems. Appliances, lights, and electronics receive reliable current. It helps systems stay stable in everyday use. Furthermore, the PCE PCD 12V 65Ah Deep Cycle Battery includes sturdy construction for long-lasting durability. The strong casing protects internal cells against wear and tear. This adds confidence in heavy use environments. Performance remains consistent over time. Also, the battery supports deep discharge recovery for extended service life. It recovers well even after heavy drain cycles. In addition, the PCE PCD Deep Cycle Battery is easy to install in many setups. It fits most battery holders and racks without fuss. Connections remain secure and simple. Furthermore, the PCE PCD Deep Cycle Battery supports stable performance in varying temperatures. It remains reliable in moderate heat and cold. This helps outdoor and mobile applications. Overall, the PCE PCD 12V 65Ah Deep Cycle Battery delivers strong power, lasting durability, and smooth performance. It fits home, marine, solar, and backup use. This battery is ideal for users who want dependable deep cycle energy every day. Specifications: Voltage : 12V Capacity : 65Ah
The Twist Online High Frequency UPS 2KVA TWUP2000/HF provides continuous backup power for servers, workstations, and networking equipment. It uses online double conversion technology for stable and clean power delivery. Additionally, the high-frequency design improves efficiency and reduces transfer interruptions. Moreover, the UPS includes an LCD display for real-time monitoring and system alerts. It also features internal 4x12V/9Ah batteries for backup operation during outages. Therefore, it protects connected devices from voltage fluctuations, overloads, and power failures. Furthermore, the TWUP2000/HF supports pure sine wave output for sensitive electronics and professional equipment. It also includes overload, short-circuit, and surge protection for safer operation. Additionally, the compact tower design fits office, server room, and IT environments easily. Specifications: 2KVA online double conversion UPS technology Internal 4x12V/9Ah rechargeable batteries LCD display for real-time monitoring Pure sine wave output for stable power delivery Overload and short-circuit protection system
Specifications : UPS Type Tower Phase Single phase with ground Rating (VA) 10000 Nominal Power (W) 8000 Standard ModelDimension (mm) 442 x 190 x 688 (D x W x H) Weight (kg) 66 Long-run ModelDimestions (mm) 442 x 190 x 318 (D x W x H) Weight (kg) 16 INPUT Connection Type Terminal Nominal Voltage 208/220/230/240VAC Voltage Range 110-300 VAC (Load at 50%)176-300 VAC (Load at 100%) Frequency Range 46~54 Hz or 56~64 Hz Power Factor >= 0.99 OUTPUT Connection Type Terminal Output Voltage 208/220/230/240VAC Voltage Regulation ±1% Frequency Range (Synchronized Range) 46~54 Hz or 56~64 Hz Frequency Range (Batt. Mode) 50Hz or 60Hz +/-0.1Hz Current Crest Ratio 3:1 Harmonic Distortion ≤3% THD (Linear load)≤5% THD (Non-linear load) ALARM & INDICATORS Battery Mode Sounding every 4 seconds Low Battery Sounding every second Overload Sounding twice every second Fault Continuously sounding LCD Load level, Battery Level, AC mode, Battery mode, Bypass mode and Fault CONNECTIVITY, CONTROL & MONITORING Front panel Status LED, Function keys, LCD display Communication Smart RS232*USB Port Emergency Power Off (EPO) BATTERY Standard ModelType 12V / 9Ah Numbers 16 Typical Recharge Time 9 hours recover to 90% capacity Long-run ModelType Depending on the capacity of external batteries Number 16 ~ 20 (Adjustable) Charging Current (max) 1A/2A/4A/6A (Adjustable, 6A is only available for 16pcs batteries) manufacturer link
INVO online INH1000 NVO Online UPS High Frequency 10000 VA, LCD Display Inbuilt Battery 16 x 12V/9 Ah Specifications: Specifications : AC Input Bypass AC Output Battery Fault Screen LCD AC Input Bypass AC Output Battery Fault Screen LCD 1 year warranty Manufacturer Link
The APC UPS 600W 1000VA Line Interactive BV1000I-GR provides reliable backup power for home and office devices. First, it delivers line-interactive output to protect equipment from voltage fluctuations. In addition, it safeguards connected devices against surges, spikes, and short outages. Moreover, the compact design allows easy placement on desks or near electronics. Finally, the UPS includes LED indicators to monitor battery and load status. The BV1000I-GR ensures uninterrupted operation and protects important electronics during power interruptions. Specifications: 600W / 1000VA line-interactive output protects devices Safeguards against power surges, spikes, and outages Compact design for easy placement on desks or near electronics LED indicators monitor battery and load status Ensures uninterrupted operation during short power interruptions
Features • Advanced DSP and 3-level technology • Output power factor 1.0 • Active power factor correction (APFC), input power factor up to 0.99 • High efficiency 95% (up to 98% in ECO mode) • Advanced digital parallel technology • Wide input voltage range (11 0 – 288 Vac) and frequency range (40 -70Hz) • 50 I 60 Hz frequency auto sensing • Two modes of frequency conversion: 50 Hz input I 60 Hz output or 60 Hz input I 50 Hz output • Dual-input design, supporting independent bypass • Flexible battery configuration (settable 16-20 pes batteries) • Digitally controlled charger • High charging current available (Max. 12 A) • Charging voltage and current configured by demands • Linear derating in low voltage input reducing battery discharging times, extending the service life of battery • Intelligent battery management, automatic floating I equalizing charge control, charger dormancy control, increasing battery life by 50%• Ability to switch on the UPS with batteries • Settable delayed start time when mains power is restored, reducing the impact on power grid or generator • Fan speed varies intelligently with temperature, reducing noise and extending its service life • Equipped with self-aging function • Compact internal layout, miniaturized the complete unit for small footprint • LCD+LED display, multi-functional keys operation, friendly human-machine interface • Powerful background software for parameters configuration • Advanced multi-platform communications: RS232, USB, RS485, SNMP and dry contacts communication interfaces • Effective software and hardware protection function, robust self-diagnostic function, and abundant event log for check Available Options • RS232 and smart card slot included • Optional parallel function, battery temperature compensation, SNMP card, USB, RS485 card, dry contacts, EMD, and SMS alarms Rear Panel 1. RS232 2. EPO 3. Parallel Port (optional) 4. USB (optional) 5. Temperature Detection (optional) 6. Intelligent Slot 7. Reserved: for manual bypass or battery breaker or outlets ect. 8.Fans 9. Bypass Breaker 10. Input Breaker 11.GND 12.Terminals and Cover http://en.eastups.com/EA900G4610kVA/6754.jhtml
The Beco GP600 600VA 360W UPS delivers reliable power protection for home and office devices. It keeps your electronics safe during outages and voltage drops. This UPS helps prevent data loss and sudden shutdowns, providing peace of mind every day. Moreover, the Beco GP600 600VA 360W UPS features 600 VA capacity with up to 360 W output power. It supports computers, routers, modems, and monitors effortlessly. Devices continue running smoothly during short power interruptions. This improves system stability. In addition, the UPS includes built-in surge protection for safe operation. It guards connected devices against spikes and surges. This adds an extra layer of defense during storms or unstable power conditions. Safety remains a priority. Furthermore, the Beco GP600 600VA 360W UPS offers battery backup that keeps equipment running long enough to save work. This prevents data corruption during sudden outages. Users can shut down systems properly. Protection feels dependable. Also, the unit delivers stable voltage regulation without manual adjustment. It corrects fluctuations automatically. This improves device performance and lifespan. Steady power enhances everyday use. In addition, the Beco GP600 600VA 360W UPS includes easy-to-read LED indicators. They show power and battery status at a glance. Users stay informed without confusion. Monitoring becomes simple and quick. Moreover, the UPS features multiple outlets for connecting several devices at once. This increases flexibility for workstations and entertainment setups. You can protect more devices with one unit. Furthermore, the Beco GP600 600VA 360W UPS supports simple installation without complicated steps. Setup is quick with clearly marked connections. This helps both beginners and experienced users. Also, the compact design fits well on desks or shelves without taking much space. It blends into home and office environments easily. Portability stays practical. Overall, the Beco GP600 600VA 360W UPS delivers dependable battery backup, surge protection, and steady power. It protects vital electronics and supports uninterrupted use. This UPS is ideal for users seeking reliable power protection every day. Specifications: 600VA, 360W, LED, Plastic Case Input: 145-290 VAC Output: 230VAC 50/60HZ 12V 7AH *1pc, Universal Socket *2 + EU Plug With AVR, Bypass output Overload and short circuit protection
APC UPS Accessories SURT48XLBP APC Smart-UPS RT 48V 1/2KVA SURT models Battery Pack
The Twist Online High Frequency UPS 6KVA TWUP6000/HF provides continuous backup power for servers, networking systems, and critical equipment. It uses online double conversion technology for stable and clean power delivery. Additionally, the high-frequency design improves efficiency and reduces transfer interruptions. Moreover, the UPS includes an LCD display for real-time monitoring and system alerts. It features internal 16x12V/9Ah batteries for backup operation during outages. Therefore, it protects connected devices from voltage fluctuations, overloads, and sudden power loss. Furthermore, the TWUP6000/HF supports pure sine wave output for sensitive electronic equipment. It also includes overload, short-circuit, and overheating protection for safer operation. Additionally, the tower design fits office, server room, and IT environments easily. Specifications: 6KVA online double conversion UPS technology Internal 16x12V/9Ah rechargeable batteries LCD display for real-time monitoring Pure sine wave output for stable power delivery Overload and short-circuit protection system
Prolink PRO906WS 6KVA / 4800W Online UPS with AVR is a high-performance power backup solution designed for critical devices, servers, and sensitive electronics. It provides stable and continuous power protection against outages and voltage fluctuations. It features a 6000VA (4800W) capacity with pure sine wave output. Therefore, it ensures clean and reliable power delivery for computers, networking equipment, and industrial systems. In addition, it protects devices from sudden power loss and electrical damage. The UPS uses online double-conversion technology with built-in AVR (Automatic Voltage Regulation). As a result, it delivers consistent voltage output and improves equipment safety during unstable power conditions. It supports heavy-duty usage and long backup operation depending on load. Meanwhile, its robust design makes it suitable for business, IT infrastructure, and professional environments. Prolink designs its UPS systems for reliability and protection. Therefore, this model is an ideal choice for users who need uninterrupted and stable power supply for critical operations. manufacturer link Specifications: 6000VA / 4800W high capacity Pure sine wave output Online double-conversion UPS Built-in AVR voltage regulation Ideal for servers and critical systems
Specifications : Le grand ups keor spx 800va 310301 1year warranty ups 800va
Features • Advanced DSP and 3-level technology • Output power factor 1.0 • Active power factor correction (APFC), input power factor up to 0.99 • High efficiency 95% (up to 98% in ECO mode) • Advanced digital parallel technology • Wide input voltage range (11 0 – 288 Vac) and frequency range (40 -70Hz) • 50 I 60 Hz frequency auto sensing • Two modes of frequency conversion: 50 Hz input I 60 Hz output or 60 Hz input I 50 Hz output • Dual-input design, supporting independent bypass • Flexible battery configuration (settable 16-20 pes batteries) • Digitally controlled charger • High charging current available (Max. 12 A) • Charging voltage and current configured by demands • Linear derating in low voltage input reducing battery discharging times, extending the service life of battery • Intelligent battery management, automatic floating I equalizing charge control, charger dormancy control, increasing battery life by 50% • Ability to switch on the UPS with batteries • Settable delayed start time when mains power is restored, reducing the impact on power grid or generator • Fan speed varies intelligently with temperature, reducing noise and extending its service life • Equipped with self-aging function • Compact internal layout, miniaturized the complete unit for small footprint • LCD+LED display, multi-functional keys operation, friendly human-machine interface • Powerful background software for parameters configuration • Advanced multi-platform communications: RS232, USB, RS485, SNMP and dry contacts communication interfaces • Effective software and hardware protection function, robust self-diagnostic function, and abundant event log for check Available Options • RS232 and smart card slot included • Optional parallel function, battery temperature compensation, SNMP card, USB, RS485 card, dry contacts, EMD, and SMS alarms Specifications Voltage range OUTPUT Output wiring Rated voltage Voltage regulation Frequency Waveform Power factor Total harmonic distortion (THDv) Crest factor Overload BATTERIES DC voltage Number of battery lnbuilt battery (standard model) Charging current Recharge time EM Efficiency Transfer time Protections Max. number of parallel connections Communications Display OTHERS Operating temperature Storage temperature Relative humidity Altitude !Prating Noise level at 1 m Dimensions (W x D x H) (mm) Packaged dimensions (W x D x H) (mm) Net weight (kg) Gross weight (kg) 110- 176 Vac (linear derating between 50% and 100% load); 176- 288 Vac (no derating) Single-phase three-wire (1 Cll + N + PE) 208 (PF=0.9) 1220 1230 1240 Vac ± 1% Synchronized to bypass in mains mode; 50 160 Hz±0.1% Hz in battery mode Sinusoidal 1 s 1% (linear load); s 4% (non-linear load) 3:1 105%- 110% for 10 min, 110%- 125% for 1 min, 126%- 150% for 30 s 192 Vdc (192- 240 Vdc settable) 16 pes (16- 20 settable) 12VI7Ahx16 I 12VI9Ahx16 Standard model: 1 A; Long time model: 5A(default), 1 – 5Asettable, 12A (optional) Standard model: 90% capacity restored in 8 hours; Long time model: depend on the capacity of battery ~ 94% at 100% load, max. 95% at 60% load,~ 98% in ECO mode Oms Short-circuit, overload, overtemperature, battery low voltage, overvoltage, undervoltage and fan failure 4 RS232 (standard), USB I RS4851 dry contacts I SNMP I baltery temperature compensation (optional) LCD+ LED O”C – 40″C -25″C – 55″C (without battery) 0 – 95% (non-condensing) s 1 000 m, derating 1% for each additional 1 00 m IP20 S55dB S58dB 191 X 465 X 711 (S), 191 X 465 X 350 (H) 191 X 495 X 711 (S), 191 X 495 X 350 (H) 310 X 654 X 941 (S), 318 X 595 X 475 (H) 310 X 685 X 941 (S), 318 X 617 X 475 (H) 53 (S), 14.5 (H) 62 (S), 16.5 (H) 61 (S), 16 (H) 70 (S), 18 (H)
The SkyGate Mini DC UPS 20000mAh is a powerful and compact solution for uninterrupted power. Whether you need backup power for your router, modem, or other devices, this mini UPS has you covered. With a 20000mAh capacity, the SkyGate Mini DC UPS ensures your devices stay powered during outages or unexpected power cuts. This high-capacity battery provides extended usage time, keeping your essentials running smoothly. The SkyGate Mini DC UPS is designed for versatility, featuring multiple output options. It supports DC 9V/12V, USB 5V, and Type C, making it compatible with a wide range of devices, from routers to smartphones. Setting up the SkyGate Mini DC UPS is simple and hassle-free. Its plug-and-play functionality allows you to connect your devices quickly, ensuring uninterrupted power with minimal effort. The SkyGate Mini DC UPS is equipped with intelligent safety features, including overcharge protection, over-discharge protection, and short-circuit protection. These features ensure safe and reliable operation, protecting your devices from damage. Compact and portable, the SkyGate Mini DC UPS is easy to carry and store. Its lightweight design makes it perfect for use at home, in the office, or even on the go. In conclusion, the SkyGate Mini DC UPS 20000mAh offers reliable backup power with a high-capacity battery and versatile output options. Keep your devices running smoothly during power outages with this efficient and portable mini UPS. Specifications: Battery : 20000mAh Output Power : 18W POE Port : 24V/0.7A DC Port : 9V/2A, 12V/1.5A Output Ports : 5V/2A USB, 5V/1A Type-C
General Topology Online double conversion Configuration Tower Part Number 9E3000I Rating (VA/Watts) 3000/2400 Dimensions (H x W x D, mm) 399 x 330 x 190 Weight (kg) 24.2 Warranty 2 years Electrical Input Connection (1) IEC-320-C20 Input Voltage Range 176-300V without derating (up to 100-300V with derating) Nominal Voltage 208/220/230/240V Frequency 50/60 Hz autoselection Frequency Range 40-70 Hz Electrical Output Voltages 208V*/220V/230V/240V ±1% Voltage THD <2% for 100% linear load Outlets (6) IEC-320-C13 (1) IEC-320-C19 Overload Capacity 105%-130% : 60s, 130%-150% : 10s,>150% : ≥ 300ms Efficiency (Normal Mode) Up to 91% in Online mode Output Frequency 50/60 Hz autoselect Communications Communication Ports 1 USB port + 1 RS232 serial port (USB and RS232 ports cannot be used simultaneously) Communication Slot 1 slot for Network-M2, ModBus-MS or Relay-MS cards Power Management Software Intelligent Power Editions Environmental & Standards Audible Noise <37 dB @ typical load Operating Temperature 0 to 40°C Safety markings IEC/EN 62040-1 EMC Markings IEC/EN 62040 -2 Approvals CE, CB report (TUV)
Specifications : Brand HAWK Package Dimensions 59.2 x 54.5 x 19.8 cm; 9 Kilograms Item model number HAWK202011 Manufacturer HAWK Wattage 720 watts Are Batteries Included Yes Item Weight 9 kg
Max Configurable Power (Watts) 6.0kWatts / 6.0kVA Efficiency at Full Load 94.0 % Output Frequency (sync to mains) 50/60 Hz +/- 3 Hz Sync to mains Other Output Voltages 220 V, 240 V Load Crest Factor 3 : 1 Topology Double conversion online Waveform type Sine wave Bypass Internal bypass (automatic and manual) Input Input frequency 40 – 70 Hz Input voltage range for main operations 110 – 300 Adjustable (half load), 176 – 300V Efficiency at Full Load 94.0 % Other Input Voltages 220 V, 240 V Batteries & Runtime Battery type Lead-acid battery Typical recharge time 3hour(s) Battery Charge Power (Watts) 373 Watts Runtime View Runtime Graph View Runtime Chart Communications & Management Interface Port(s) DB-9 RS-232, Intelligent Smart Slot, USB Control panel Multifunction LCD status and control console Audible Alarm Alarm when on battery : distinctive low battery alarm : overload continuous tone alarm Emergency Power Off (EPO) Yes Available SmartSlot™ Interface Quantity 1 Surge Protection and Filtering Surge energy rating 600Joules Physical Maximum Height 685MM, 68.5CM Maximum Width 190MM, 19.0CM Maximum Depth 374MM, 37.4CM Net Weight 54.0KG Shipping weight 66.0KG Shipping Height 910MM, 91.0CM Shipping Width 290MM, 29.0CM Shipping Depth 495MM, 49.5CM Color Black Environmental Operating Temperature 0 – 40 °C Operating Relative Humidity 0 – 95 (Non-condensing) % Operating Elevation 0 – 3000meters Storage Temperature -15 – 60 °C Storage Relative Humidity 0 – 95 (Non-condensing) % Storage Elevation 0 – 15000meters Audible noise at 1 meter from surface of unit 55.0dBA Protection Class IP20 1 YEAR WARRANTY
The Twist Line Interactive UPS 850VA TWUP850/LI provides backup power protection for computers, networking devices, and office electronics. It uses line interactive technology with automatic voltage regulation for stable power delivery. Additionally, the built-in 12V/7Ah battery supports continued operation during power interruptions. Moreover, the UPS includes LED status indicators for clear system monitoring. It also supports cold start functionality for startup without direct AC power. Therefore, it helps protect connected devices from voltage fluctuations and sudden outages. Furthermore, the compact tower design fits easily in home and office environments. The system also includes overload and short-circuit protection for safer daily operation. Additionally, the simulated sine wave output supports common desktop and networking equipment. Specifications: 850VA line interactive UPS technology Built-in 1x12V/7Ah rechargeable battery LED indicators for power status monitoring Automatic voltage regulation for stable output Overload and short-circuit protection system