A-B 1746-P2 SLC 500 modular power supplies

SLC 500 Power Supplies

Switching the barrel control

For some applications, even though the loops are independent with

no thermal conduction between zones, barrel control might provide

better performance than non–barrel control. If a loop has any of these

characteristics, you might want to use barrel control if the:

• time constant is greater than 10 - 30 seconds

• loop has a problem of overshooting the setpoint

• loop output is saturating (CV is at 100%) for a significant duration

Output response

When the slot for this module is disabled, configuration words in the

SLC processor’s output image table are held in their last state and not

transferred to the module. When the slot is re–enabled, output image

table words are transferred to the module during the subsequent scan.

Barrel Control

Select barrel control for multiple–zone applications in which there is

thermal conduction between the zones. Injection molding and

extrusion are good example applications because they use multiple

heater bands (zones) mounted on one thermal conductor (the metal

barrel). The barrel conducts heat between different zones. If you

select barrel control, also select between inner and outer zones (word

1, bit 13 for channel 1). A barrel loop is autotuned as the temperature

rises from a cold start to a temperature setpoint during startup.

TC Break Control

Word 4 or O:e.8 for Channel1

If a loop input circuit becomes open (open wire) the loop can not

measure temperature. In automatic mode, the lack of temperature

feedback makes it impossible to control the temperature. To guard

against this condition, the BTM module provides TC break detection.

When a break is detected, the module responds in one of these ways:

• disables the loop

• forces CV to this (TC Break Control) value (word 4 for loop 1)

• forces the CV to the manual %–output value (O:e.8 for loop 1)

Once the thermocouple break has been repaired you must disable the

loop and then re-enable it (through the input image table O:e.0/0 loop 1).

ATTENTION ! 

Environment and Enclosure This equipment is intended for use in a Pollution Degree 2 industrial environment, 

in overvoltage Category II applications (as defined in IEC publication 60664-1), at altitudes up to 2000 m (6561 ft) without derating.

This equipment is considered Group 1, Class A industrial equipment according to IEC/CISPR Publication 11. 

Without appropriate precautions, there may be potential difficulties ensuring electromagnetic compatibility in 

other environments due to conducted as well as radiated disturbance. 

This equipment is supplied as open type equipment.

It must be mounted within an enclosure that is suitably designed for those specific environmental conditions

that will be present and appropriately designed to prevent personal injury resulting from accessibility to live parts.

The interior of the enclosure must be accessible only by the use of a tool. 

Subsequent sections of this publication may contain additional information regarding 

specific enclosure type ratings that are required to comply with certain product safety certifications. 

See NEMA Standards publication 250 and IEC publication 60529, as applicable, 

for explanations of the degrees of protection provided by different types of enclosure. 

Also, see the appropriate sections in this publication, as well as the Allen-Bradley Industrial Automation 

Wiring and Grounding Guidelines, publication 1770-4.1, for additional installation requirements pertaining to this equipment.