Siemens siprotec 7SA522, Руководство пользователя

Страница: 37 / 628

Hardware and Connections
2-7
7SA522 Manual
C53000-G1176-C119-2
Figure 2-7 Terminal block of screw terminals for current connections — rear view
The correlation between terminals and connection numbers is the same for both the
current connections and the voltage connections. Compare Figures 2-6 and 2-7.
In the terminal block for current connections, the terminals are grouped in pairs. Two
neighboring terminals such as terminals 5 and 6 form one pair. The terminal block con-
tains four pairs, one for each of the input currents.
The current transformers present low burden to the main current transformers.
When the I/O board is extracted, the current circuits are automatically short-circuited
prior to the separation of the current transformers from the current circuits. This pre-
vents hazards to service personnel due to the high voltages that can occur if the sec-
ondary circuits of the current transformers are open.
When the I/O board is properly inserted into the case, the short-circuits of the current
paths are removed after the transformers of the device are connected to the terminal-
pairs.
The short-circuit feature of the relay is an important and reliable safety feature; how-
ever, the feature does not relieve the user from exercising proper care when working
with current transformer secondary circuits.
Connections to
Voltage Terminals Ring or spade lugs may be used. To maintain proper isolation of the circuits, the lugs
must be insulated or insulating sleeves must be fitted to cover the exposed crimp
zones.
The following must be observed:
Connections with cable lugs: inner diameter of lugs, 4 mm;
maximum outer width of lugs, 10 mm;
conductor with cross-section of 1 mm
2
to 2.6 mm
2
or AWG 17 to 13.
Use copper wires only!
Cable lugs of series PIDG from Messrs AMP Co. are recommended, e.g.
Ring cable lug: PIDG PN 320 565–0
Spade lug:
PIDG PN 321 233–0.
Direct cable connections: solid or stranded conductor with connector sleeve;
conductor with cross-section of 0.5 mm
2
to 3.3 mm
2
(AWG 20 to 12).
Use copper wires only!
Maximum tightening torque: 1.8 Nm (1.3 ft-lb or 16 in-lb).
8 terminal
1
2
3
4
5
6
7
8