Protector Unit
Maker and role
Phoenix Telephone and Electrical Works Limited, Manufacturer
See full details
Object detail
Accession number
1978.2024
Description
White rectangular porcelain block, with two white ceramic rods (fuses) suspended horizontally over block. Fuses are parallel with each other and are held by metal brackets. Metal post in top centre with threaded tip, previously fastened a cover over the unit.
Brief History
This is a telegraph or telephone line protector unit. It is designed to protect people and equipment from sudden or large increases in voltage which could result in an electric shock, damaged electrical equipment, or fire. Such increases in voltage could be due to lightning strikes, or fallen power lines for example. The protector unit functions as a fuse and surge protector.
Typical construction of a protector for use with domestic telephone lines would consist of a carbon protector and one of more fuses. The central carbon protector would short the circuit to earth in cases of sudden very high voltage, e.g. lightning strike, hence these were also known as lightning protectors. One or several fuses are also mounted into the protector that will blow in cases of a power line contact.
Some early protectors also contained a heat coil which was positioned between each leg of the phone line and earth. This was intended to be a slow blow device in the event of abnormally high current flow.
Similar protection devices were used at telephone exchange line terminations and was still in use until the mid 1990s.
Typical construction of a protector for use with domestic telephone lines would consist of a carbon protector and one of more fuses. The central carbon protector would short the circuit to earth in cases of sudden very high voltage, e.g. lightning strike, hence these were also known as lightning protectors. One or several fuses are also mounted into the protector that will blow in cases of a power line contact.
Some early protectors also contained a heat coil which was positioned between each leg of the phone line and earth. This was intended to be a slow blow device in the event of abnormally high current flow.
Similar protection devices were used at telephone exchange line terminations and was still in use until the mid 1990s.
Marks
PT & EW Printed
PX24 / 237 / PHC&F 2/2 Engraved
PX24 / 237 / PHC&F 2/2 Engraved
Media/Materials
Credit Line
Phoenix Telephone and Electrical Works Limited. Protector Unit, 1978.2024. The Museum of Transport and Technology (MOTAT).
Public comments
CORRECTION: When we used a two wire overhead phone system in NZ.
- Steve Miller posted 4 years ago.
This type of fuse unit was used for the phone . When we had a two overhead phone system. They are to be mounted vertical.
- Steve Miller posted 4 years ago.