Thermo Fisher Scientific Alpha pH 2000 User Manual
Page 20
Connection for panel mounting version
1.
AC mains live wire
17.
no connection
2.
AC mains neutral wire
18.
no connection
3.
AC mains protective earth wire
19.
12V Power supply
4.
Alarm relay (NO)
20.
12V ground
5.
Alarm relay common
21.
no connection
6.
Alarm relay (NC)
22.
Earth ground
7.
Wash relay
23.
no connection
8.
Wash relay
24.
Temperature ground
9.
Relay B (SP 2)
25.
Temperature input
10.
Relay B (SP 2)
26.
Temperature sense (short to terminal 25 if
11.
Relay A (SP 1)
using 2- wire RTD
12.
Relay A (SP 1)
27.
PMP, liquid ground in symmetrical mode
13.
Hold function
28.
4-20 mA temperature output, -ve terminal
14.
Hold function
29
4-20 mA temperature output, +ve terminal
15.
no connection
30.
4-20 mA pH output, -ve terminal
16.
no connection
31.
4-20 mA pH output, +ve terminal
IMPORTANT: The Alarm relay functions as an “Active Low” device i.e. it switches OFF under
Alarm condition. Therefore the Alarm display device should be connected to the ‘NC’ contacts
of the relay (5 & 6).
NOTE:
Switch or circuit breaker shall included in the building installation.
It shall be in close proximity to the equipment and within easy reach of the
operator.
It shall be marked as the disconnecting device for the equipment.