Current collecting characteristics of catenary with non-tension contact wires T. Hamada, A. Suzuki & T. Shimada Railway Technical Research Institute, Japan Abstract Feeder cables are additionally installed as a standard on DC railway lines in Japan to complement the electric characteristics of contact wires. A number of feeder messenger catenary systems with fewer parts are now adopted to integrate the functions of feeder cables and messengers. We have devised "an aluminum case overhead conductor line" which is a catenary with non-tension contact wires aiming at the development of a feeder messenger catenary system with a structure to prevent breaking of contact wires. First, we studied the optimal form of aluminum case and performed computer simulation to examine the current collecting characteristics of this catenary. We actually constructed a catenary of this type on the current collection testing equipment of RTRI and performed pantograph running tests to confirm that it had satisfactory current collecting characteristics up to the speed of 160 km/h. 1 Introduction Since the standard voltage on the narrow-gauge DC lines in Japan is 1,5OOV, a large current is needed to operate trains. This subsequently requires an excessively large feeding current. To prevent voltage drop and supplement the current capacity through the contact wire, therefore, additional cables are installed for feeding. Now, a number of feeder messenger catenary systems [l] are adopted in Japan to integrate the functions of contact wires and messengers for labor-saving in maintenance and other purposes. Although these structures have fewer parts, they require the same management as before to prevent breaking of contact wires due to partial wear and melting by arc and Joule heat. Therefore, we have studied on "an aluminum case overhead conductor line" which is a feeder messenger catenary system with fewer parts. It has non-tension contact wires to eliminate the danger of tension-caused contact wire break.
420 Computers in Railways VIII 2 Features of aluminum case overhead conductor line The aluminum case overhead conductor line is a catenary system with a rigid conductor line, which consists of feeder messengers, auxiliary contact wires (aluminum cases), and contact wjres (Figure 1). The most advantageous feature of this catenary is that the contact wire is constructed as non-tensioned, since the rigid aluminum case holds the contact wire by its own spring force and the contact wire keeps a plane by the rigidity of aluminum. As an equivalent version of overhead conductor line with non-tension contact wires, there are rigid conductor lines installed in tunnel or for underground railways. Since they are designed for short spans limited to about 5m, however it is difficult to apply the conductor lines to other sections. In contrast, this aluminum case overhead conductor line can be installed for long spans up to about 50m in general since it consists of a catenary with rigid conductor lines supported by messengers. This catenary has a feature to prevent breaking of contact wire, since it is placed under a non-tension condition even when it has worn out or softened by arc and Joule heat. Therefore, we can expect labor-saving in maintenance and high degree of operational security. I Figure 1: Aluminum case overhead conductor line 3 Examination of optimal form of aluminum case The feeder messenger centenary system adopted for the narrow-gauge line in Tokyo uses two hard-drawn copper stranded conductors (PH356mm ) for messengers. We decided that the basic composition of the aluminum case overhead conductor line should have performance equivalent to this catenary system (Table 1). The feeder messenger used for the aluminum case overhead Table 1. Basic composition of the feeder messenger catenary system
Computers in Railways VIII 42 1 conductor line assumes two specifications; one is to use a PH356mm' conductor and the other a hard-drawn aluminum stranded HAL550mm' conductor with the same current capacity. Therefore, it is necessary for the aluminum case to have a current capacity equivalent to that of PH356mm'. Under this condition, we examined the optimal form of the aluminum case. 3.1 Wind pressure load Since rigid conductor lines have a large area subjected to winds when used it in open air, it poses a problem, that large contact wire deviation is caused by wind pressure loads. As the form of aluminum case, we adopted a round shape which is not easily affected by the drag of wind pressure unlike a quadrangle. On the assumption that the total tension is 53.9kN, the same value as that of the existing feeder messenger catenary system, we calculated the contact wire deviation at the span center for the two specifications to use PH356mm' and HAL550mm2 for the messenger. Figure 2 shows the relation between the width of the side where the aluminum case with a contact wire is subjected to winds and the contact wire deviation by wind pressure (Wind velocity: 30m/s). Since the allowable value of contact wire deviation is 300mm, this calculation result shows that it is necessary to set the width of the wind-receiving side at 63mm or less. Since the width of the portion protruded by the contact wire is llmm, the aluminum case itself without a contact wire needs to set the width of the wind-receiving side at 52mm or less width. 500 1 400 13001 200,. I 20 40 60 80 100 Width of the wind-receiving side of aluminum case with contact wire Figure 2: Contact wire deviation by wind pressure 3.2 Allowable continuous current /Hard-drawn codoer stranded conductors IPH) Hard-drawn aluminum stranded conductor (HA1) Bronze contact wire (GT-M-SN) Aluminum case [mm] (Wind velocity: 30m/s) The current capacity of a conductor is limited by the conductor temperature rise due to Joule's heat. We calculated the allowable continuous current for each conductor on the conditions shown in Tables 2 and 3 so that it is kept below the allowable temperature. Table 2. Conditions for Table 3. Allowable temperature calculating temperature rise IAmbient temderature I 40 "C Insolation 0.1W/cm2 Emissivity I 0.9 /Wind velocity I O.Sm/s I I I l00"cl 100% 90 C 90 C
422 Computers in Railways VIII The calculation result of the allowable current of each conductor is shown in Table 4. Here, we set the allowable continuous current of the aluminum case as 1,050A so that it has an allowable current equivalent to that of PH356mm or HA1550mm. We found by calculation that the cross-sectional area of the aluminum case was required to be 557mm or over in order to ensure this current capacity. Table 4. Allowable continuous current PH356mm HA1550mm GT-M-SN170mm2 (Residual height: 8.5mm) Aluminum case 1,023A 979A 345A (It is set as 1,050A) 3.3 Current capacity Contact wires and messengers are heated to radiate heat whenever a train passes. Here, by using a model of train (series 201) that runs on a narrow-gauge line in Tokyo, we calculated the shortest train operation interval from the viewpoint of current capacity under the following conditions. - We used the aluminum case whose outside diameter was 52mm and cross-sectional area was 557mmz, and a PH356mm conductor for feeder messengers. We assumed the worst conditions that trains (series 201) always consume the maximum load current of 2,000A. (In powering at 50 km/h) * We assumed that the current is fed from substations A and B, and the load current for a train fed by the substation A was expressed by the triangular wave shown in Figure 3. We calculated the temperature rise of each conductor near the substation A. * We applied the conditions shown in Table 2 for the calculation of temperature rise. Figure 3: Load current for a train fed by the substation A (Triangular wave current) We calculated the temperature of each conductor according to the above conditions. Figures 4 (a) and (b) express the relation between the train operation interval and conductor temperature when the distance between the two substations is 3km and 5km, respectively. Of this model, according to the conditions of the allowable temperature of conductors (Table 3), trains can run at intervals of minimum 108 seconds and 178 seconds when the distance between substations is 3km and 5km, respectively.
Computers in Railways VIII 423 140 E 120 0 140 2120 $100 $ 80 E 2 60 $ 40 1 20 0 0 60 120 180 240 300 360 420 480 60 120 180 240 300 360 420 480 Operation interval between trains [SI Operation interval between trains [SI (a) Distance between substations: 3 h @) Distance between substations: 5km Figure 4: Relation between the train operation interval and each conductor temperature 3.4 Tensile strength Since we assumed that the auxiliary contact wire tension was 24.5kN, the tensile strength of aluminum case was set at over 53.9N with a safety factor of 2.5. The tensile strength is 108kN when the cross-sectional area of aluminum case is set at 557mm to satisfy the above condition. 3.5 System height We calculated the minimum hanger length on the assumption that the messenger tension was 29.4kN, and span length was 50m. When we assume a standard system height (850mm) equivalent to that of existing feeder messenger catenary system in Tokyo, the calculated minimum hanger length (183mm) satisfies the standard regulation value (150mm or over). 3.6 Examination result From the above examination result, the optimal form of the aluminum case is as follows. - A round aluminum case is adopted to minimize influence of wind pressure. It is necessary to set the diameter at 52mm or less based on the relation with the allowable value of contact wire deviation. It is necessary to set the cross-sectional area of the aluminum case at 557mm2 or over in order to have electric performance equivalent to the existing catenary system. - When the messenger tension is set at 29.4kN; the auxiliary contact wire tension at 24.5kN and the system height at 850mm, the tensile strength and minimum hanger length satisfy each condition. 4 Simulation of current collecting characteristics By computer simulation, we calculated the contact loss rate and the contact wire uplift at a support of the aluminum case overhead conductor line which used the aluminum case with the optimal form examined above. Since the auxiliary
424 Computers in Railways VIII contact wire and contact wire of the aluminum case overhead conductor line are in close contact, we performed simulation by assuming that the sums of mass and tension of the auxiliary contact wire and the contact wire could be treated as a constant for one contact wire, and that this system was a simple catenary. Table 5 shows the catenary composition, and Table 6 the property of pantograph when performing simulation. The simulation result of the contact loss rate of the 2nd pantograph is shown in Figure 5. The contact loss rate was 0% in both pantographs up to the maximum-speed of 160 km/h on a narrow-gauge line. The simulation result of the contact wire uplift at the support is shown in Figure 6. It is not over allowable value of 70mm in either pantograph up to the speed of 200km/h. (*The allowable value of the contact wire uplift at a support point is designed small, and the static upward force of a pantograph is also small in Japan.) Messenger Contact wire Span length Hanger interval System height PH356mm2 (Tension: 29.4kN) Aluminum case + GT-M-SN170mmZ 50m 5m 850mm (T ension: 24.5W) 10 9 3 6 8 8 7 f 6 - g 5 z 4 2 3 $ 2 1 0 70 7 60 E - t 50 70 90 110 130 150 170 190 210 70 90 110 130 150 170 190 210 Figure 5: Simulation result of contact loss rate Figure 6: Simulation result of contact wire uplift at support
5 Test by current collection testing equipment We designed the aluminum case to have the cross-sectional form shown in Figure 7 based on the examination result. We actually constructed the aluminum case overhead conductor line by using this aluminum case as an auxiliary contact wire on the current collection - testing equipment of RTRI, and performed a test of current collecting characteristics. (The construction of the photograph is shown in Figure 8.) The equipment used for this test has a full length of 500m and can carry out running tests up to a speed of 160km/h, by using actual contact wires and pantographs. Computers in Railways VIII 425 Cross-sectional area: 564.7mm2 Mass per unit length: 1.52kg/m Figure 7: Cross-sectional form of aluminum case Figure 8: Construction of aluminum case overhead conductor line 5.1 Test conditions 5.1.1 Composition of catenary The catenary composition of the testing equipment is shown in Table 7. The feeder messenger was tested for two conductor sectional areas PH356mm2 and HAL550mm. The edge of the aluminum case used for the auxiliary contact wire is connected with a wire of St135mm2, and tensioned by a wheel tension balancer. 5.1.2 Tension change We assume that the tension changes by temperature and other factors when the catenary is actually constructed, and tested the case when the tension of the messenger and the auxiliary contact wire changed 210%.
426 Computers in Railways VIII PH356mm HAL550mm Feeder messenger Standard tension: 29.4kN Standard tension: 29.4kN Auxiliary Aluminum case (Cross-sectional form is shown in Figure - 7), contact wire Standard tension: 24.5kN Contact wire I GT-M-SN170mm Tension: OkN Span length 50m Hanger interval 5m System height 850mm Table 8. Test conditions 5.2 Test items We measured the contact loss rate, contact wire uplift, and aluminum case strain. Figure 9 shows the catenary composition on the current collection testing equipment, together with the measuring point for uplift and strain (support, span center, and hanger point). 850mm k a support 50m support A d Figure 9: Catenary composition on the current collection testing equipment
Computers in Railway VIII 427 5.3 Test results We used conductors of PH356mm and HA1550mm2 as the feeder messenger. However, there were no differences between the two conditions in terms of the current collecting characteristics. Figures 10 to 13 shows the test results when a conductor of PH356mm is used for the feeder messenger. 5.3.1 Comparison of characteristics between pantograph types The current collecting characteristics of the two types of pantographs (PS21, PS32) are shown in Figures 10 and 11. The tension was set at the standard value, 29.4kN for the messenger and 24.5kN for the auxiliary contact wire. 5.3.1.1 Contact loss rate The test result of the contact loss rate is shown in Figure 10. In the case of PS21 that has a large positive upward aerodynamic force property, the contact loss rate was nearly 0% up to 160 km/h, and the current collecting characteristics were extremely good. In the case of PS32, the contact loss rate was 1% or less up to 120km/h, to show good current collecting characteristics, and about 2% at 130km/h to 160km/h, which was a usually allowed value. 5.3.1.2 Contact wire uplift at support The test result of contact wire uplift at support is shown in Figure 11. It takes a maximum value of 8.8mm with PS21 and 5.3mm with PS32. These values are considerably lower than the allowable value of contact wire uplift at support (70mm). -1 0 E9 va CI e7 s6 - g5,4 E; s1 0 70 90 110 130 150 170 Figure 10: Test result of contact loss rate!*o 10 so 70 90 110 130 150 170 Figure 11: Test result of contact wire uplift at support 5.3.2 Comparison of characteristics between different values of tension The current collecting characteristics of PS21 are shown in Figures 12 to 13, in the case where the tension of messenger and auxiliary contact wire change 210%. 5.3.2.1 Contact loss rate The test result of the contact loss rate is shown in Figure 12. Under the standard tension, +lo% tension, and -10% tension, the contact loss rate was nearly 0% up to 160 km/h, and the current collecting characteristics were extremely good. The contact loss was not affected even if the tension changes about 210%.
428 Computers in Railways VIII 5.3.2.2 Contact wire uplift at support The test result of constant wire uplift at support is shown in Figure 13. The contact wire uplift does not increase even if tension changes, but remains considerably lower than the allowable value. A-10% tension 4 30 OStandard tension 0+10% tension A-10% tension $3 98aaer4e 70 90 110 130 150 170 70 90 110 130 150 170 Figure 12: Test result of contact loss rate 5.4 Conclusion of the test Figure 13: Test result of contact wire uplift at support When an aluminum case overhead conductor line is composed as shown in Table 7, both the contact loss rate and the support uplift satisfy the allowable values. We understood that trains can run at 160 km/h by using the pantographs PS21 and PS32. Even when the tension changes 210% by temperature or for other reasons, the current collecting characteristics do not change much to prove that there are no problems for train operation. Moreover, when a conductor of HA1550mm2 is used for the feeder messenger, the same characteristics as those of a conductor of PH356mm2 are maintained. In the actual case where two or more pantographs are used, and the state of catenary is considered to be worse than that of this testing equipment, however, field running tests need to be performed for final judgment. 6 Conclusion Based on this research, we devised "an aluminum case overhead conductor line" which is a catenary with non-tension contact wires. This was to develop a feeder messenger catenary system with a structure to prevent breaking of contact wires due to tension. First, we determined the optimal form of an aluminum case. Then, we actually constructed this catenary on the current collection testing equipment of RTRI and performed the running test of pantographs. We confirmed that the current collecting characteristics of this system were good up to the speed of 160 km/h. To actually use this system in the future, it is necessary to investigate the problems in constructing it at high places during a short construction period on actual railway lines. References [l] A. Iwainaka, A. Suzuki & Y. Shimodaira, Development of single copper feeder messenger wire for overhead contact lines, Computers in Railways VII, pp.703-712, 2000