Backup Power Automatic Transfer NIPSCO Energy Symposium symposium Backup Power Applications/Considerations Backup Power Types Automatic Transfer Switch Basics Presenters McGill Power - Jeremy Irmeger Eaton - Barry Graves 2007 Eaton Corporation. All rights reserved.
Objective & Agenda Bypass Isolation Magnum Front Access Objective Understanding the basics of how to identify and properly apply UPS s Uninterruptible Power Supplies) and ATS (Automatic Transfer Switches) for accommoding for seamless systems. Agenda What is a UPS UPS Types What is a Automatic Transfer Switch Transfer Switch Types Transfer Switch Application Categories Transition Types Basic Components of a Transfer Switch Application Considerations Questions
The 9 Common Power Problems Interruption Sag Swell Undervoltage Overvoltage Line Noise Frequency Variation Switching Transients Harmonic Distortion
3 (+1) Basic Types of UPS Standby Off Line Normal Operation Power Failure Event Powerware Series 3 The Series 3 (Stand-By) UPS delivers power protection from 3 of the most common power problems that threaten your equipment and data Interruption Sag Swell Line Interactive Buck/Boost Powerware Series 5 The Series 5 (Line-Interactive) UPS delivers power protection from 5 of the most common power problems that threaten your equipment and data Undervoltage Overvoltage Ferroresonant +1 Powerware Series Ferro The Series Ferro UPS delivers galvanic isolated power protection from 8 of the most common power problems that threaten equipment and data Harmonic distortion Line noise Switching transients On Line Double Conversion ( Powerware Series 9 The Series 9 (On-Line) UPS delivers power protection from all 9 of the most common power problems that threaten your equipment and data Frequency variation
What is a UPS System? Maintenance Bypass Panel System Input N.O. System Output To PDU AC DC AC UPS Power Module 1. Double Conversion 2. Online System Battery Cabinet
How Much Downtime is Acceptable? Power Availability Equivalent Power Disruptions (yr) 99.9999999% ISPs, e-business, Communications, Electronics mfg. N+ Redundancy < 3 seconds 99.999% Food Processing Server Operating Systems Generators and Some UPS 5.3 minutes 99.99% 99.9% Hospitals, Airports Generator Only Residential Homes Typical Grid Power 0.88 hours 8.8 hours
Automatic Transfer Switch A device which transfers electrical loads between two sources of power by using either manual or automatic controls. UTILITY LOAD GENERATOR UTILITY UTILITY
Bypass Isolation Transfer Switch An automatic transfer switch with an additional bypass isolation switch Provides ability to perform maintenance of the main transfer switch power device, without interruption of power to the load Applied in high reliability applications: Provides emergency power to life safety and other critical loads
Transfer Switch Types There are only two ways to transfer power: Automatic If loads are very critical, an automatic transfer switch would probably be used insure the fastest possible transfer. Non-Automatic (manual, or electrically operated) If loads are not quite as critical, but still cannot go for any extended period of time without power, a Non-Automatic or manual transfer switch could be used.
Non-automatic vs Manual Transfer Electrically operated non-automatic transfer switches. The switch electrically transfers power when a pushbutton, usually mounted on the switch s enclosure, is pushed. If necessary, the switch can also be manually operated. Manually initiated, Electrically operated Manually operated transfer switches provide all the mechanics to effect the transfer from source to source. The actual transfer of power, however, is by true hand operation of the transfer switch. Manually initiated, Manually operated
Application Category NFPA 70 National Electric Code NFPA 70 - National Electric Code Article 700 - Emergency Systems Article 701 - Legally Required Standby Systems Article 702 - Optional Standby Systems Article 708 - COPS Article 517 - Health Care Facilities NFPA 99 - Health Care Facilities NFPA 110 - Emergency & Standby Systems NFPA 20 - Fire Pumps NFPA 70E Workplace Safety
Article 700 Emergency Systems Article 701 Legally Required Article 702 Optional Systems Article 708 COPS Application examples include any system where a power interruption would create life safety or health hazards. Must automatically transfer in 10 seconds Shall be listed for emergency use (UL 1008 only). Shall supply only emergency loads. Application examples include any system where a power interruption would create hazards or hamper rescue or fire fighting operations. Must automatically transfer in 60 seconds Shall be listed for emergency use (UL 1008 only). Application examples include any system where a power interruption would cause discomfort or disrupt a process. Automatic/manual transfer. No transfer time requirement. Allows for option as such as: Go to neutral position Auto/Manual Selector switch Application examples include emergency call centers ATS labeled for use on emergency systems. No requirement for transfer time. Transfer equipment separate from other emergency, legally required, or optional loads. Must include provisions for roll-up generator if using one generator.
Transfer Switch Transition Types 2007 Eaton Corporation. All rights reserved.
Open Transition Also called a break-before-make switch. One set of contacts opens before the other set closes There is a definite break in power as the load is taken off one source and connected to another. This is the most common and least expensive Normal Loads TS N TS E Emergency
Delayed Transition Break Both Sides Delayed Transition One set of contacts opens before the other The other set of contacts delays in closing Load is disconnected from power during all transfers Normal Loads TS N TS E Emergency
Delayed Transition Time delay neutral Requires a 3 position mechanism Timed delay in the neutral position, typically 0-120sec 3 sec is typically a good starting point Load Voltage Decay Senses back emf voltage Will pause in neutral position until regenerative voltages are at 10-30% On Eaton transfer switches option 32 cannot be reprogrammed in the field. A new controller must be purchased. 32a 32b
Closed Transition Normal Loads TS N TS E Emergency 100 m/secs overlap-time
Closed Transition Closed Transition is also called a make-before-break switch. There is no interruption in power to a critical load when using this type of switch. Both power sources are connected to the load before the break occurs. Parallels the loads for < 100ms The two power sources have to have the same voltage and frequency and be synchronized for the switch to transfer. Permits the periodic testing of an emergency source, such as a generator, without interrupting power to the loads
Consideration for selecting Transition Types When transferring two live sources, abnormal motor inrush current can occur leading to possible damage of motor windings, insulation, couplings and in some cases, the load itself. Inrush currents are caused by the motor s residual voltage being out of phase with the voltage source to which it s being transferred. Methods of control are: Open Inphase transfer Motor load disconnect control circuit Delayed transition - Time Delay Neutral, Load Voltage Decay Closed transition less than 100 ms paralleling of sources
Open In-phase Transfer 32f Feature that allows a live transfer between two sources only when the phase difference between the two is near to zero. This feature prevents in-rush currents from exceeding normal starting currents in the case where motor loads are being transferred How it works: Monitor samples the relative phase angle between the two sources being transferred When the two sources are within the desired phase angle different and are approaching zero phase angle difference, the inphase monitor signals the transfer switch to operate. The operating time of the transfer switch is key in utilizing an inphase monitor (must transfer in less than ten cycles) In-phase monitor and VFD s do not work well together, use TDN. In-phase doesn t give the VFD s time to reset.
Motor Load Disconnect Control Circuit 45 Selected motor loads are de-energized during transfer operation Controller signals contact to open approx. 3 seconds prior to transfer, thus de-energizing selected loads. Loads are turned onto the generator after a designated time delay. Loads can be turned on at one time or sequentially so as to not block load the generator. Motor load disconnect works well when the generator is sized at the min.
Automatic Transfer Switches - Main Components 2007 Eaton Corporation. All rights reserved.
Transfer Switch Main Components An automatic transfer switch (ATS) is made up of several main components Controller Continually monitors the condition of the power sources Initiates start command to backup generator, Initiates transfer and retransfer to good power source Power switching device Power device rated to transfer the load to/from the power sources Control Power Transformer panel Supplies operational power to the switching device/controller
Main Components - Controller In an ATS, the controller is basically the brains of the ATS, that contains all the logic/intelligence to initiate the switching. The controller performs following functions: Senses the source voltage and frequency Sends a start command to the back up power if the main source is lost. Commercial ATC-300+ Controller
Main Components Switching Device The switching device is the main power device that transfers the load from one power source to another. The switching device includes the main power device and the transfer mechanism. The ATS controller tells the switching device when to make the transfer/retransfer to a good source Two basic types of switching devices: Contactor Specifically designed contactors to perform load transfer between to AC sources. Transfer switches do not use motor starting/lighting type contactors. Molded Case/Power Case Switch A molded case or power case circuit breaker without and /or with a trip unit. Used when a circuit requires a compact, high capacity disconnect device.
Main Components Contactor Switching Device Contactor based The contactor switching device includes the main power assembly and the operating mechanism. The power assembly is composed of the individual power poles. The operating mechanism includes the solenoid and the mechanical interlock. Power Assembly 3 Pole Contactor Source 2 Bus Moving Contact Source 1 Bus Load Bus Operating Mechanism Single Power Pole
Main Components Molded Case or Power Case Circuit Breaker Switching Device Molded Case or Power Case Circuit Breaker Based The molded case/power case circuit breaker switching device is a circuit breaker without and/or with the overcurrent trip. The switching device is composed of two separate power devices. One device is for closing on source 1 and the other for closing on source 2. The operating mechanism includes the motor operator. 3 Pole Molded Case Switch Power Assembly 3 Pole Power Case Switch Power Assembly Motor Operating Mechanism Source 1 Device Source 2 Device Motor Operator in Power Case Switch
Main Components Transformer Panel Control Power Provided by small Control Power Transformers CPT- connected to the normal and the emergency source. The good source then provides the control power needed for the ATS to properly operate. Provided with a multi tap primary allowing the CPT to be used on different voltage applications permitting a simple field change from one voltage to another.
Basic Information for ATS Selection When selecting a Transfer Switch, review the following: Types of load to be transferred Transition type Open In phase, Delayed, Closed Transition Application Type Life Safety, Emergency, Optional Switch Ratings Voltage rating, Phase, # poles Continuous Current rating/amps Overload and fault current withstand ratings Configuration Type Service Entrance Bypass Isolation
UPS and ATS Basics Questions?