4Annunciator Relays MR 10, MRE 10, MR 21 and MRE 21
Application
The annunciator relay MR 10 is used for indication of fault and
operating conditions in control rooms, switchboards as well as
mimic diagrams. Because of its large indicating area and the rigid
design, this relay is ideally suited for any environmental condition.
Alarge number of annunciator relays can be assembled in banks.
Construction
The annunciator relay MR 10 is a semi-automatic relay that can be
activated optionally by NO or NC input contacts. The required
control is adjusted by simply changing the position of two operating
screws on the bell crank. For the optical display no additional
auxiliary voltage is necessary beside the coil energizing voltage.
This is especially important for applications where the relay is used
for the supervision of voltages.
Function
In the normal condition the indicating area is black. With the action
of the relay the indicating flag (a white area with legend) becomes
visible. Simultaneously the auxiliary contacts are actuated. By
pressing the reset button below the indicating flag the message is
acknowledged. The indicating flag remains visible but with an
additional area of red/white hatched lines. Simultaneously the
contacts are restored to their normal position. After clearance of the
fault the indicating flag returns to its normal postion automatically.
In addition to the operation described above the relay is also
available with contacts directly driven by the armature. This type is
used mainly in remote control stations.
Diagrams: pages 6 and 7
Features
Easily exchangeable legend plate. Operational in any position.
Heavy duty contacts. Tropicalized version is available, if desired.
Mounting
Individual relays
Panel surface mounting
Accessories: mounting screws with nuts
Dimension print: page 9
Panel flush mounting
Accessory: brace
Dimension print: page 9
Panel flush mounting plug-in type
Accessories: socket, mounting brackets
Dimension print: page 9
Relay banks
Up to 100 annunciator relays can be installed in one bank.
Dimension print: page 10
Banks of annunciator relays can be installed in steel cabinets for
panel surface mounting, wall surface mounting, wall flush mounting
or for mounting on the floor. Bus-wiring of the relay banks can be
neatly achieved using conducting angles of different heights and
special connecting wires. Relay banks in housings for surface
mounting can be wired in the factory, or by the client.
Supplementary type: Ground fault annunciator relay MRE 10
Application
The annunciator relay MRE 10 is a semi-automatic relay which is
used for ground fault indication in three-phase systems.
Function
The relay is equipped with two coils and must be connected to the
open delta winding of a voltage transformer. The relay responds at
30 V AC. With the responding the second coil is connected in
series with the first to allow operating voltages up to 100 V AC. The
ground fault indication relay can also be supplied for other voltage
ranges. The further functions correspond to relay MR 10.
Diagram: page 7
Mounting
Similar to annunciator relay MR 10
Supplementary type: Annunciator relay MR 20
Application
Similar to annunciator relay MR 10
Function
The annunciator relay MR 20 operates fully-automatically. A
manual reset and a possibility for the adjustment from normally
de-energized to normally energized are not provided. Upon
response the contacts are actuated and the legend becomes
visible. With the clearance of the fault the legend disappears
automatically and the contacts return to their normal position.
Diagram: page 8
Mounting
Similar to annunciator relay MR 10
