Buchholz Relay BR25 / BR50 / BR80

Description and general specifications.
The gas and oil actuated (Buchholz) relay is designed to detect faults as well to minimize the propagation of
any damage which might occur within oil-filled transformers, capacitors and reactors supplied with oil
conservator.
The relay is therefore particularly effective in case of:
 Short-circuited core laminations
 Broken-down core bolt insulation
 Bad contacts
 Overheating of some part of the windings
 Short-circuits between phases
 Earth faults puncture of bushing insulators inside tank
Furthermore the relay can prevent the development of conditions leading to a fault in the transformer, such
as the falling of the oil level owing to leaks, or the ingress of air as a result of defects in the oil circulating
system.

Construction.
Casing : non porous weatherproof compact casting of light aluminium alloy painted.
Cover : non porous weatherproof compact casting of light aluminium alloy painted. On the cover are located : the terminal box, the valve of pneumatic test, the breather cock, the button for mechanical test of alarm and trip circuits.
Inspection windows : special tempered glass with graduated scale in cm3.
Contacts : they can be mercury switches or magnetic actuated switches (reed contacts). On request itís possible to supply change-over switches.
Switches characteristics :
ï rated voltage : 24  250V AC or DC
ï rated current : 0,5A (1 0000 tests)
ï breaking capacity : 2A AC (cos= 0,4  25% - 50Hz) 2A DC (T=L/R=40msec).
Mechanical protection degree : IP 54

Insulation : 2000V 50Hz between terminals and earth for a 60 seconds time.
Working temperature : oil temperature range: - 25 / +115°C.
Vibration test (in normal operative conditions) :
ï oscillation amplitude : 2mm
ï time diagram :
0Hz  1 00Hz 30 sec.
1 00Hz (200 vibrations/sec.) 60 sec.
1 00Hz  0Hz. 30 sec.
Contacts capacity to withstand vibrations :
Mercury sw :
150 horizontal vibrations/sec. (75Hz) first signals of closing contacts 1 20 vertical vibrations/sec.
(75Hz) first signals of closing contacts.
Magnetic sw :
200 horizontal vibrations/sec. (1 00Hz) no one signal of closing contacts 200 vertical vibrations/sec. (1 00Hz)
no one signal of closing contacts.