All Clear: How a UPS operates to clear faults

Transcription

1 All Clear: How a UPS operates to clear faults 12 th /13 th March Alex Emms Operations Director Kohler Uninterruptible Power

2 Company Overview Uninterruptible Power Supplies Ltd (UPSL) founded First 3ph transformerless UPS in UK&I First 3ph transformerless modular UPS in UK&I UPSL acquired by Kohler Power Group UPSL Sales & Service operations in Singapore Kohler Co. acquires Pure Power Systems, Ireland 1997 Critical Power Protection Solutions UPSL renames to become Kohler Uninterruptible Power UPS & Emergency Lighting Single and Three Phase systems Transformerless UPS from 1kVA to 5 MVA BS EN Kitemarked emergency lighting Modular & Standalone 10kVA to 3.3MVA Choice of engine manufacturers Service Excellence Nationwide 24/7 Service Maintenance & Response Contracts Remote Monitoring Best in Class Customer NPS rating ISO9001, ISO14001, OHSAS Years of Experience c.100 Employees Installed UPS Base Service Contracts +90% First Time Fix Rate

3 Content 1. How does the UPS react to a downstream fault. 2. Fault clearance with static bypass. 3. Fault clearance without static bypass. 4. Q&A 3

4 How does a UPS react to a fault downstream Inverter has limited fault clearing capability. eg. 2.5 In for 100mS Bypass supply has high fault clearing capabilities. eg. 10 In for 10mS Short Circuit!! 4

5 How does a UPS react to a fault downstream? SHORT CIRCUIT Fault occurs downstream Is the fault >150%? Is the bypass available? Transfer load to the static bypass Has the fault cleared? Return load to Inverter OVERLOAD Overload timer activated Fault cleared within time? Return to rmal Operation Inverter gives max. short circuit current Short circuit timer activated Bypass or UPS protection operates Has the fault cleared? Inverter turns off. Return to rmal Operation 5

6 Fault clearance on Bypass BS th Edition Chapter 55 Other Equipment Additional requirements for installations incorporating static convertors Where fault protection for parts of the installation supplied by the static convertor relies upon the automatic closure of the bypass switch and the operation of protective devices on the supply side of the bypass switch is not within the time required by Section 411, supplementary equipotential bonding shall be provided between simultaneously accessible exposed-conductive-parts and extraneous-conductive-parts on the load side of the static convertor in accordance with Regulation

7 Fault clearance on Bypass BS7671 section Allows for the use of the static bypass to operate downstream protective devices supplied by a UPS under certain circumstances. Short Circuit!! By using the static bypass supply the protective device must operate in the required time (0.4 sec or 5 sec) This is not permitted when supplying a safety service (see section ). 7

8 Fault clearance on Inverter Chapter 56 Safety Services Uninterruptible power supply sources (UPS) Where an uninterruptible power supply is used, it shall: (i) be able to operate distribution circuit protective devices, and (ii) be able to start the safety devices when it is operating in the emergency condition from the inverter supplied by the battery, and (iii) comply with the requirements of Regulation , and (iv) comply with BS EN and BS EN , as applicable. Examples of safety services include (this list is not exhaustive): - Emergency lighting - Fire evacuation systems - Fire pumps - Smoke ventilation systems - Fire rescue service lifts - Fire services communication systems - Fire detection and alarm systems - Essential medical systems - CO detection and alarm systems - Industrial safety systems 8

9 How does a UPS powering safety services react to a fault downstream? SHORT CIRCUIT Fault occurs downstream Is the fault >150%? Chapter 56 Safety Services Transfer load to the static bypass Has the fault cleared? Return load to Inverter OVERLOAD Overload timer activated Fault cleared within time? Return to rmal Operation Inverter gives max. short circuit current Short circuit timer activated Bypass or UPS protection operates Has the fault cleared? ncompliant Return to rmal Operation 9

10 Fault clearance on Inverter BS The inverter must be capable of operating both the protective devices and the dependent safety services. Short Circuit!! The Inverter must be able to operate the protective device in the required time (0.4 sec or 5 sec) in all circumstances. The inverter must also be capable of handling any start-up currents of the connected load without using the static bypass. 10

11 System design implications For systems covered by BS th Edition Chapter 56 (Safety Services) Need to increase the size of the UPS inverter to operate protection devices and clear faults as bypass cannot be used. This can increase operating costs unless the inverter is of a modular type that can switch down significantly. Alternatively, reduce the size / activation current of the protective devices being used in the system, so an inverter better matched to the load can activate them. 11

12 Additions to the 18 th Edition BS th Edn. Chapter 41 Protection against Electric Shock 419 PROVISIONS WHERE AUTOMATIC DISCONNECTION ACCORDING TO REGULATION IS NOT FEASIBLE Where automatic disconnection is not feasible in circumstances where: (i) electronic equipment with limited short-circuit current is installed, or (ii) the required disconnection times cannot be achieved by a protective device the provisions of Regulations and are applicable For installations with power electronic convertors with nominal voltage U0 greater than 50 V AC or 120 V DC and where automatic disconnection is not feasible, the output voltage of the source shall be reduced to 50 V AC or 120 V DC or less in the event of a fault between a live conductor and the protective conductor or Earth in a time as given in Regulation , or , as appropriate (see BS EN ). The power electronic convertor shall be one for which the manufacturer gives adequate methods for the initial verification and periodic inspection and testing of the installation. 12

13 Additions to the 18 th Edition SHORT CIRCUIT Fault occurs downstream Is the fault >150%? Is the bypass available? Transfer load to the static bypass Has the fault cleared? Return load to Inverter OVERLOAD Overload timer activated Fault cleared within time? Return to rmal Operation Inverter gives max. short circuit current Short circuit timer activated Bypass or UPS protection operates Has the fault cleared? Reduces Voltage in Reqd Time Return to rmal Operation 13

14 System design implications BS7671 Chapter UPS voltage reduction must take place in required time ask manufacturer. Chapter 41 voltage reduction approach can not be used for safety services. Chapter 41 does NOT allow for the shutdown of the inverter to be used as disconnection in all situations. This could be used for non safety services that would normally use the static bypass to operate the protective device ONLY when the bypass is not available (I.E. during a mains failure). te - This will also shutdown all connected loads. 14

15 Questions? Alex Emms DCW Stand D920 15