32 AMP Single Phase Power Filter

Transcription

1 32 AMP Single Phase Power Filter Mil Std Part 1 is a military document titled HIGH ALTITUDE ELECTROMAGNETIC PULSE (HEMP) PROTECTION FOR GROUND-BASED C4I FACILITIES PERFORMING CRITICAL, TIME URGENT MISSIONS. This describes the protection and testing required for these types of facilities. Points of Entry (POE s) are devices to enter the HEMP protected facility and cover all penetrations including doors, ventilation vents, pipes and electrical cables. These filters are single line symmetric HEMP filters POE (Point of Entry) protective devices for ELECTRICAL CABLES. A full description of electrical POE s is given in paragraph 5.7 of Mil Std Part 1. General Specification: Rated Voltage Single Phase Filters : 250V AC 50/60Hz Three Phase Filters : 250/440V AC 50/60Hz Rated Current & Insertion Loss: See graph and table Maximum Temperature Rise on Full Load: 25 0 C Operating Temperature: 40 C + 50 C Storage Temperature: 40 C + 70 C Each Filter Comprises the Following: 1 no. Backing plate HEMP Filter Line Units (4 no. for Three Phase and Neutral circuits, 2 no. for Single Phase and Neutral circuits) 1 no. Cable Entry Enclosure (design and dimensions of this can be varied to suit customer s requirements) 1 no. Cable Exit Enclosure (design and dimensions of this can be varied to suit customers requirements) Filter design allows HEMP filter modules to be replaced without the need to disconnect the input and output cables. Page 1 of 7

2 Injected Pulse Characteristics for HEMP Power Filters Class of POE Type of injection Peak short circuit current (A) Rise time FWHM (s) Full width at Half Maximum amplitude Short pulse Common mode 5,000 < 20 ns 50 µs 55 µs Short pulse Wire to Ground 2,500 < 20 ns 50 µs 55 µs Intermediate pulse Common mode 250 < 1.5 µs 3 ms 5 ms Intermediate pulse Wire to Ground 250 < 1.5 µs 3 ms 5 ms Technical Specifications Single phase and neutral (SPN) Note 1 Three phase and neutral (TPN) Rated current (A) Rated Voltage (v) Maximum leakage current (A) see note 1 Maximum let through current (A) see note 2 Max Heat Dissipation SPN/TPN (W) Max Heat Dissipation SPN/TPN (Btu/Hr) EEP 32SPN EEP 32TPN /440 0, /30 51/102 EEP 64SPN EEP 64TPN /440 1, /55 102/188 EEP 100SPN EEP 100TPN /440 1, /90 153/306 EEP 250SPN EEP 250TPN / / /512 EEP 400SPN EEP 400TPN / / /852 At 250V / 50 Hz Note 2 At 2500 A at 20/500 ns rise time Insertion Loss. The higher the Insertion Loss the greater the filter performance. Insertion Loss, generally expressed in Decibels, is the ratio of the power received before the insertion of the EMC Filter to the power received after the insertion of the EMC Filter. The insertion loss is measured in the frequency domain and for EMP applications the spectrum is usually between 50Hz and 1GHz, however frequencies outside of this spectrum can be tested. Insertion loss testing is generally measured in the asymmetric (Common) mode in a balanced 50 Ohm impedance system. The main specifications for filter testing are BS613 and MIL. STD. 220A. If the filters supplied use toroidal current compensating inductor technology the tests can be conducted without full load current being passed through the filter at the time of tests. This is because current compensating filter inductors do not saturate and therefore the performance does not alter as the load current changes. Page 2 of 7

3 The measurements are taken by using a tracking/signal generator and spectrum analyser. The signal sweeps across the frequency range and is passed through the test leads, which are coupled directly, and received by the spectrum analyser. This signal is then normalised to the 0dB. The filter is then inserted in the circuit and the test repeated. As the signal has been normalised to 0dB prior to the filter being added in series the true Attenuation or Insertion Loss of the filter is directly displayed. By sweeping continuously across the frequency spectrum, and not at discrete frequencies, any resonant frequencies or manufacturing imperfections which can cause a reduction in filter performance can be identified. It must be recognised that insertion loss measurements made in a 50 ohm system, while giving good guidance and comparative performance figures, may differ from those achieved in practical situations. This is because although mains supplies are assumed to be 50 Ohm as far as RFI is concerned in practise the terminating impedance can be somewhat different. Insertion Loss into 50 ohm load as per Mil Std 220 Frequency (MHz) Insertion Loss (db) Filters for HEMP When using asymmetric filters, the assumption is made that any radiated RF would couple equally and balance into all conductors at once. But in real life no two signals are ever identical or perfectly balanced and any imbalance in a system carrying common mode signals can create a voltage difference between the conductors giving rise to differential signals. A common mode inductor would allow passage of differential signals. The chance that a High-Altitude Electromagnetic Pulse (HEMP) will arrive equally on all power lines is very low. That signals will arrive just right for an asymmetric filter to stop them is highly unlikely given atmospheric conditions, propagation of the wave, number of electrons released, distance between power lines, etc. In HEMP applications, the EMP will arrive chaotically and unpredictably at the Points of Entry (POE). Filters should be able to reject symmetric signals. If asymmetric only filtering is used, not only will the signals get through, but these unpredictable signals (some of which could be of very high amperage) could cause an imbalance in the common core of the asymmetric filter which would lead to instantaneous saturation of the core(s) and total loss of protection to any form of electromagnetic energy. Page 3 of 7

4 Conclusion Symmetric (differential mode) and asymmetric (common mode) signals are different types of signals that may be present in conductors. It is also clear that these may be removed by using symmetric filters. Asymmetric filters can only remove asymmetric signals. While asymmetric filters are generally physically smaller than the symmetric filters, the use of asymmetric filters must be very carefully evaluated or unwanted differential mode signals may inadvertently pass through the filtering network and compromise overall system performance. FOR HEMP PROTECTION SINGLE LINE SYMMETRIC FILTERS MUST BE USED Dimensions (mm) B D (SPN Filters) E (TPN Filters) C Page 4 of 7

5 Individual Filter Line Dimensions (excludes input and output boxes) Filter Rating (A) Length (mm) A Width (mm) B Depth (mm) C Single Phase and Neutral Filter (2 Lines) (excluding input/output boxes) Filter Rating (A) Length (mm) A Width (mm) D Depth (mm) C Three Phase and Neutral Filter (4 Lines) (excluding input/output boxes) Filter Rating (A) Length (mm) A Width (mm) E Depth (mm) C Input box (for SPN Filters 2 lines) Filter Rating (A) Length (mm) D Width (mm) G Depth (mm) C Page 5 of 7

6 PRODUCT DATASHEET Output box (for SPN Filters 2 lines) Filter Rating (A) Length (mm) D Width (mm) F Depth (mm) C Input box (for TPN Filters 4 lines) Filter Rating (A) Length (mm) D Width (mm) G Depth (mm) C Output box (for TPN Filters 4 lines) Filter Rating (A) Length (mm) D Width (mm) F Depth (mm) C Page 6 of 7

7 European EMC Products European EMC Products Ltd was established in July 1996 to supply high quality products and services to the Electromagnetic Compatibility (EMC) market. Quality European EMC Products are registered to BS EN ISO 9000:2008, certificate No. FS License scope: The design, assembly, servicing and testing of RF Shielded structures and equipment including EMI shielding and thermal management materials; Gas tight doors; and specialised mobile electromagnetic pulse protected (EMPP) containers. Page 7 of 7