Sinrace Power Supply Technology (Shenzhen) Co., Ltd.
Why choose Sinrace?
What true advantages you will have if you choose us?
We are a professional manufacturer of power supply with 16years' history already, and we are always with you for offering you answers on power supply questions and supplying you with enthusiastic services. The emphasis and the main responsibility for us is to meet our customers's needs unceasingly.We believe those customers are our partners who shall build long-time and reliable business relationship with us.
Certifications
| Why telecom power supply has -48V dc power supply? |
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In earlier days of telephone networks, 48V DC was once found to be suitably high to be able to make telephone work on long telephone lines and still low enough not to cause serious danger if somebody touches the telephone wires. Telephone central offices (exchanges) so started using 48V DC. Even when newer automatic exhanges were setup, they were designed to make use of existing 48V battery sets and arrays which were available with telecom service providers. This legacy design practice has been continued and over many decades all new telecom devices have been designed to work with 48V. The positive grounded or -48V system is also from telephone history. The negative voltage on the line was better than positive to prevent electro-chemical reactions from destroying the copper cable quickly, if cables get wet Ans- It is because of cathodic protection. It reduces the sulphation on the battery terminals. Note: There are comments associated with this question. See the discussion page to add to the conversation. |
