HT instruments HT950N - Manual (Page 10)

HT950N
EN - 10
5.2.2. Temperature probes
WARNING
 Input circuits (2U, 2V, 2W, 1F) operates with small signals therefore its
necessary to execute a separated wiring from relay command output circuits,
supply circuit and from other power circuit.
 We always recommended to connect of each Pt100 to use a shielded
cable with shield connected from meter front only. Connect at S terminal
(31) the shield of each thermoresistance, like shown on Fig. 3.
 Resistance of each Pt100 connection cable must be 5 max and each of
three conductors must have the same resistance. I value is over 5
 is
possible to have a reading error at display. You can refer at the following
Table 1 to obtain correct measurements.
Lenght Pt100 conductor from transformer connector to HT950N meter
Twisted conductor Single conductor
0.5 mm
2
…… about 100 m
0.75 mm
2
…. about 150 m
Diameter 1.0 mm…..about 150 m
Diameter 1.2 mm…..about 250 m
Diameter 1.6 mm…..about 400 m
Table 1: conductors section on HT950N connection
5.2.3. CONTR output circuit
The output circuit CONTR can be used to connect a forced ventilation system or a parallel
device installation. The electrical scheme of connection is presented on following Fig. 6.
Fig. 6: CONTR relay on no alarm condition (normally disabled)
CONTR relay operate a commutation in the following cases:

When HT950N measures a temperature over UA threshold CONTR is activated.

When HT950N measures a temperature under UF threshold CONTR is disabled.
CONTR relay can be more important for operators on solution of various installations
problems.