PD48-1000FH High-resistance distribution cabinet (part1).pdf

PS48/1000HF High Impedance Distribution Cabinet

Users Manual

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Emerson Network power Co., Ltd.

PS48/1000HF High Impedance Distribution Cabinet

Users Manual

Publishing State: Standard Date April, 2001 BOM 31010361

Copyright 2001 by Emerson Network Power Co., Ltd.

All rights reserved.

The information in this document is subject to change without

notice. No part of this document may in any form or by any

means (electronic, mechanical, micro-copying, photocopying,

recording or otherwise) be reproduced, stored in a retrieval

system or transmitted without prior written permission from

Emerson Network Power Co., Ltd.

Publication Statement

Introduction of the Content

This manual expounds the operating principle, installation and

application of 2 types of high impedance distribution cabinet,

namely PD48/1000HF/16D and PD48/1000HF/30D. It is

applicable to users and service engineers for their reference

during installation and application.

Readers

Users and service engineers

Contents

Chapter 1 Overview ................................................................................................1

1.1 Low/High Impedance Distribution ..............................................................1

1.2 High Impedance Distribution Cabinet Series .............................................3

Chapter 2 Operating Parameters & Principle..........................................................5

2.1 Environmental Conditions..........................................................................5

2.2 Working Parameters ..................................................................................6

2.3 Operating Principle ....................................................................................6

Chapter 3 Design References...............................................................................11

3.1 Calculation of Load Cable Resistance .....................................................11

3.2 Internal Resistance of Battery..................................................................12

Chapter 4 Installation and Application ......................................

4.1 Unpacking Inspection ..................................................

4.2 Installation ...................................................................

4.2.1 Cabinet Fixing....................................................

4.2.2 Installation of Top Cover and Door ....................

4.2.3 Earthing .............................................................

4.2.4 Connection Between Cabinets ..........................

4.2.5 Connection of Load Cable .................................

4.3 Start up ........................................................................

4.4 Series Connection of High Impedance Strips ..............

Chapter 5 Safety Protections ....................................................

5.1 Electrical Insulation......................................................

5.1.1 Insulation Resistance.........................................

5.1.2 Dielectric Strength .............................................

5.2 Earthing System ..........................................................

5.2.1 DC Operation Earthing ......................................

5.2.2 Protective Earthing ............................................

Chapter 1 Overview 1

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Chapter 1 Overview

1.1 Low/High Impedance Distribution

In the power supply systems for communication equipment, there exist 2 power distribution modes, i.e., low impedance distribution and high impedance distribution.

In low impedance distribution , as the load power cables are relatively short (hence with smaller feeding resistance), in the event of short circuit in a certain branch load, the power source voltage will drop sharply, affecting the operation of other branch loads, and the extra short circuit current will damage the battery as well.

While in power supply systems of high impedance distribution, as each load branch features high impedance much larger than the internal resistance of the power source , the transient voltage of the power source resulting from short circuit of a certain load branch will be limited within a certain range without affecting the operation of other load branches.

In order that the load branch has high impedance, it is normal practice to use a user cable of certain sectional area as the power feeding cable. If the distance between the distribution cabinet and the exchange power source frame is short, an additional series-connected resistor can be added into the power feeding circuit to increase the total resistance value.

The following gives an example of the impact of load short circuit on power source voltage in low impedance and high impedance distribution systems. Battery voltage Ub=54V, total internal resistance of the battery Ri=4m, as shown in Fig. 1-1. In a low impedance distribution system, when the power feeding cable resistance Rd=2m, the load short circuit current Ishort and the distribution cabinet voltage Ud will respectively be:


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Ishort= Ub/Ri+Rd= 54/4+210-3= 9000A Ud= Ub- RiIshort= 54-410-39000= 18V In a high impedance distribution system, when the power feeding cable resistance Rd=35m, the load short circuit current Ishort and the distribution cabinet voltage Ud will respectively be:

Ishort= Ub/Ri+Rd=54/4+3510-3=1385A Ud= Ub- RiIshort= 54410-31385= 48.5V In a high impedance distribution system, when the power feeding

cable resistance Rd=20m, the load short circuit current Ishort and the distribution cabinet voltage Ud will respectively be:

Ishort= Ub/Ri+Rd=54/4+2010-3=2250A Ud= Ub- RiIshort= 54410-32250= 45.0V

=

exchange

Distributioncabinet

Rd

Rectifiermodule

RiIshort

Ub

Ud

Fig.1-1 Shorts in DC distribution systems

SPC exchanges must be operated within a certain basic voltage range, ultra-high or ultra-low basic voltage would severely affect their normal operation. For example, AXE-10 SPC exchange made by Sweden requires the basic voltage to be -44~-54V, and NEAX-61 SPC exchange made by Japan requires the basic voltage to be -43~-58V. It can be seen from the above examples that in the event of load shorts, the distribution cabinet voltage of the low impedance distribution system drops by 2/3, which obviously can not meet the power supply requirement of the exchange , while the voltage drop


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of the high impedance distribution cabinet is only 5~9V, which can meet the power supply requirements of the exchange.

1.2 High Impedance Distribution Cabinet Series

Avansys has specially developed and produced high impedance distribution cabinets PD48/1000HF/16D and PD48/1000HF/30D to meet the needs of the SPC exchanges requiring high power feeding resistance made by Huawei Technologies Co, Ltd. Inside the cabinet , each load branch is provided with an additional resistor with a fixed resistance value. There is a shorting strip at both ends of the resistor, setting open the shorting strip can series-connect the resistor with the power feeding cable, thus increasing the total resistance of the power feeding circuit.

PD48/1000HF/16D has dual 16 outputs of 48V/63A with the function of dual inputs/dual outputs.

PD48/1000HF/30D has dual 30 outputs of 48V/32A with the function of dual inputs/dual outputs.

Structure of PD48/1000HF/16D high impedance distribution cabinet is shown in Fig. 1-2.

Structure of PD48/1000HF/30D high impedance distribution cabinet is shown in Fig. 1-3.


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Fig. 1-2 PD48/1000HF/16D High Impedance Distribution Cabinet

Fig. 1-3 PD48/1000HF/30D High Impedance Distribution Cabinet

Chapter 2 Operating Parameters & Principle 5

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Chapter 2 Operating Parameters & Principle

2.1 Environmental Conditions

Installation site: altitude no higher than 2000 meters

Work temperature: -5~40 Storage temperature: -40~70

Relative humidity: 90%402 Atmospheric pressure: 70~106kPa

Installation sites should be free of conductive dusts and corrosive gases.

Installation sites should be free of vibration and bumping, and the vertical inclination of the site should be less than 5 degrees.


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2.2 Working Parameters

Table 2-1 Working Parameters of High Impedance Distribution

Cabinets

Model

Working parameters

PD48/1000HF/16D PD48/1000HF/30D

Rated voltage -48V -48V

Input voltage range -40~-60V -40~-60V

Batteries that can be connected.

None None

Rated current 1000A 1000A DC

inpu

t

Input cable access mode

Top/bottom cable access

Top/bottom cable access

Rated voltage -48V -48V

Branch output 48V/63A dual 16 outputs

48V/32A dual 30 outputs

Output impedance 15m 30m

DC

out

put

Output cable exit mode

Top/bottom cable exit Top/bottom cable exit

Dimensions hwd 2100876550 (mm) 2100876550(mm)

Mec

hani

cal

para

met

ers

Weight 75kg 85kg

2.3 Operating Principle


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The operating principles of PD48/1000HF/16D and PD48/1000HF/30D high impedance distribution cabinets are respectively shown in Fig. 2-1 and Fig. 2-2.

Fig. 2-1 Schematic Diagram of PD48/1000HF/16D (dual 16 outputs)

The 2 positive and negative busbars of PD48/1000HF/16D high impedance distribution cabinet are respectively connected with the 2 groups of output positive and negative busbars of the rectifier cabinet. If there is only one group of rectifier cabinet input, then the high impedance distribution cabinet can be used as a single 32-output distribution cabinet.


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Fig. 2-2 Schematic Diagram of PD48/1000HF/30D (dual 30 outputs)

The 2 positive and negative busbars of PD48/1000HF/30D high impedance distribution cabinet are respectively connected with the 2 groups of output positive and negative busbars of the rectifier cabinet. If there is only one group of rectifier cabinet input, then the high impedance distribution cabinet can be used as a single 60-output distribution cabinet.

The positive and negative busbars of the distribution cabinet are connected respectively with the positive and negative output busbars of the rectifier cabinet. Each branch output is composed of MCB, high impedance strip (including shorting strip) and output connection terminal. The alarm board B241HFC1of PD48/1000HF/16D high impedance distribution cabinetor B141HFC1of PD48/1000HF/30D high impedance distribution cabinetmonitors the ON/OFF status of


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each branch output by means of signal sampling. In dual power supplies, when short circuit or overload of one of the power feeding circuit causes MCB trip, the alarm light goes on and the buzzer will beep, alerting that the load in is single power supply status and faces potential power-off.

When the branch works normally, the corresponding alarm light is in OFF status. Of the three panel switches, MUTE switch is used to silence the alarm sound; TEST switch is used to test whether the LEDs on the display panel are damaged; while MONITOR ON/OFF switch is used to enable/disable the alarm function of the alarm board.

Notice: During system operation, irrespective of whether the output branch is connected to load, the MCB is required to be in close status, or else, the system will alarm.

Chapter 5 Safety Protections 11

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Chapter 3 Design References When the resistance of each load power cable is larger than 30m, the high impedance strip can be short-connected. That is because in such case the resistance of the load power cable is already much larger than the internal resistance of the power source, even if shorts occur on the load, normal power supply to other loads by the power source will not be affected.

At delivery of high impedance distribution cabinet, the high impedance strips of all branch outputs are short-connected. If calculation shows that the load cable resistance can not meet the requirement of high impedance distribution (that is, the load cable resistance is less than 30m), it is recommended to connect the high impedance strip in series. Please refer to Section 4.4 for the detailed procedures.

3.1 Calculation of Load Cable Resistance

The linear resistance R (in ) of a load power cable can be calculated according to the following formula:

R= 0L / S[1+(T-T0)] 0: resistivity of copper at 20, 0=0.0179mm2/m; : resistance temperature coefficient of copper, =0.0039-1; L: cable length, unit: m;

S: sectional area of the cable, unit: mm2;

T: ambient temperature for cable operation, unit: ; T0: reference temperature 20; For example: at 20, the resistance R of a 25m long copper core load cable with 15mm2 sectional area is 30m. At 20, the resistance R of a 17 m long copper core load cable with 10mm2 sectional area is 30m.


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In the above two cases, the load cable resistance is no less than 30m, so the high impedance strip can be short-connected.

3.2 Internal Resistance of Battery

Internal resistance of different types of batteries are different, please refer to the product specifications of the battery manufacturer. Table 3-1 shows the internal resistance of some types of batteries made by American company POWER.

Table 3-1 Internal resistance of some types of batteries made by

POWER

Battery type Battery internal resistance(m)PRC_1225X 9.0

PRC_1230X 8.6

PRC_1235X 7.4

PRC_1245X 6.4

PRC_1250X 5.8

PRC_1265 6.2

PRC_1280X 5.1

PRC_1290X 4.5

PRC_12100X 4.3


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PD48-1000FH High-resistance distribution cabinet (part1).pdf