Thermo Fisher Scientific Alpha pH 190 (In the process of updating the brand guideline & product image) - Manual (Page 41)

- 35 -
Appendix 4: External Relays
The relays on the Alpha pH 190 series controller are rated for 6
amps at 110 VAC and can be wired directly to your final control
element (provided its power requirements does not exceed this).
However, to preserve the life of your controller, or if higher power is
needed, it is recommended that you use the controller relay to drive
an external relay.
Diagram below shows a typical installation. Wiring should be
changed appropriately if normally closed (N.C.) operation is desired.
+
4 -
20
m
A
12
19
3 11
18
2 10
17
1 9
16
8
15
7
14
6
13
5 4
NC NC NC NC
- 4 -
20
mA RE
L
A Y 1
- N
O
RE
LA
Y 1
-
P O
LE
RE
L
A Y 1
- N
C
P t 1
00 -
G
N
D
RE
LA
Y 2
- N
O
Pt
1 0 0 -
IN
R E L A Y 2
- PO
L
E
Pt
1
00
- SEN
S E
GR
O
U
N D
RE
L
A Y 2
- N
C
N LI
Q U
ID
G
N D
L
pH/ORP
WARNING
10 9