WIRING CONNECTIONS
After the unit has been mechanically mounted, it is ready to be wired. All wiring connections are made to the rear screw terminals. When wiring the unit, use the numbers on the label and those embossed on the back of the case, to identify the position number with the proper function.
All conductors should meet voltage and current ratings for each terminal.
Also cabling should conform to appropriate standards of good installation, local codes and regulations. It is recommended that power supplied to the unit
(AC or DC) be protected by a fuse or circuit breaker. Strip the wire, leaving approximately 1/4" (6 mm) bare wire exposed (stranded wires should be tinned with solder). Insert the wire under the clamping washer and tighten the screw until the wire is clamped tightly.
Caution: Unused terminals are NOT to be used as tie points. Damage to the controller may result if these terminals are used.
SIGNAL WIRING
Thermocouple (T48)
When connecting the thermocouple, be certain that the connections are clean and tight, refer to Figure 4 for terminal connections. If the thermocouple probe cannot be connected directly to the controller, thermocouple wire or thermocouple extension-grade wire must be used to extend the connection points (copper wire does not work). Always refer to the thermocouple m a n u f a c t u r e r ’ s
Figure 4, Thermocouple Connection recommendations for mounting, temperature range, shielding, etc. For multi-probe temperature averaging applications, two or more thermocouple probes may be connected to the controller (always use the same type).
Paralleling a single thermocouple to more than one controller is not recommended. Generally, the red wire from the thermocouple is negative and connected to the controller’s common.
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RTD (T48)
When connecting the
RTD, be certain that the connections are clean and tight, refer to Figure 5 for terminal connections. RTD sensors have a higher degree of accuracy and stability than thermocouple sensors. Most RTD sensors available are the three wire type. The third wire is a sense lead for canceling the effects of lead resistance of the probe. Four wire RTD elements may be used by
Figure 5, RTD Connection leaving one of the sense leads disconnected. Two wire RTD sensors may be used in either of two ways:
A) Attach the RTD to terminals #8 and #10. Install a copper sense wire of the same wire gage as the RTD leads. Attach one end of the wire at the probe and the other end to terminal #9. Complete lead wire compensation is obtained. This is the preferred method.
B) Attach the RTD to terminals #8 and #10. Install a shorting wire between terminals #9 and #10, as shown in Figure 5, RTD Connection. A temperature offset error of 2.5°C/ohm of lead resistance exists. The error may be compensated by programming a temperature offset.
Note: With extended cable runs, be sure the lead resistance is less than 15 ohms/lead. For thermocouple or RTD runs longer than 100 feet, convert the signal to a current near the temperature probe. Current or 20 mA loop signals are less susceptible to noise and signal loss than long thermocouple or RTD runs. The RLC ITMA and IRMA DIN rail modules are designed for these applications. By converting the temperature signal, the P48 can be used in place of a T48.
