Claims
- 1. A protection module of an exchange connected between a telephone line pair via a main distributing frame and input terminals of a subscriber line interface board equipped at a backboard of the exchange, for protecting the subscriber line interface board from an overvoltage and an overcurrent, the protection module comprising:
- first and second means for protecting against overcurrent, respectively connected in series between the line pair via the main distributing frame and the input terminals of the subscriber line interface board of the exchange, tip and ring lines; and
- means for protecting against over voltage, connected in parallel between output terminals of said first and second means for protecting against overcurrent and the input terminals of the subscriber line interface board of the exchange, tip and ring lines, having an output line connected to ground of the subscriber line interface board of the exchange.
- 2. The extra protection module according to claim 1, wherein the overvoltage protection means includes a thyristor.
- 3. The extra protection module according to claim 2, wherein the overvoltage protecting means includes a glass tube.
- 4. The extra protection module according to claim 1, wherein the first means for protecting against overcurrent includes a positive temperature coefficient resistor.
- 5. The extra protection module according to claim 4, wherein the positive temperature coefficient resistor is made of a polymer.
Priority Claims (1)
Number |
Date |
Country |
Kind |
1990-22825 |
Dec 1990 |
KRX |
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Parent Case Info
This is a continuation of application Ser. No. 07/811,080, filed Dec. 20, 1991 now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4907120 |
Kaczmarek |
Mar 1990 |
|
4964160 |
Traube et al. |
Oct 1990 |
|
Continuations (1)
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Number |
Date |
Country |
Parent |
811080 |
Dec 1991 |
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