Modular Components - Pentair 920 Series Installation, Operating And Maintenance Instructions

1.3 moduLar Components

INDUSTRIAL HEAT TRACING SOLUTIONS
Csa C/us and c-etL-us approved
The 920 series of controllers is approved for Class I, Division 2, Groups A,B,C,D and Zone 2
hazardous locations, making it ideal for direct installation in the field. This can save the significant
expense of wiring back to a central-ly-located electrical distribution center.
The 920 series controller is made up of a number of building blocks, allowing the ultimate in
design flexibility. Each component's primary function is described below.
1.3.1 ControL moduLe
The 920 control module forms the heart of a single- or dual-point heat trace control solution. Each
plug-in module provides all of the intel-ligence required to control and monitor two independent
heat trace circuits. It includes indicators for alarm and output status and a connector for use with
a 920 Operator Console. An internal connector is provided to plug into an optional communications
interface.
The control module packaging provides a rugged, vibration-proof design. Once it is plugged into a
terminal board, the module is fastened using the two captive screws included as part of the rear
cover. It is important that these two screws be securely fastened whenever the module is powered.
1.3.2 termInaL board
The terminal board eases maintenance and troubleshooting by providing a termination point for all
of the low-voltage signals. The 920 control module may be installed or removed without disturbing
the field wiring. Temperature sensor, communications, and alarm control wiring are connected to
the lever-operated spring terminals, providing gas-tight, vibration-resistant connections.
1.3.3 operator ConsoLe
A large, easy-to-read alphanumeric display and menu-driven interface ease controller
configuration and eliminate the need for an external programmer. The console may be left
installed permanently or may be installed temporarily for display/setup during maintenance and
trou-bleshooting. Access is available for all monitored parameters, programmed values, and
alarm information. Enhanced security is provided by password protection.
The unique design of the operator console allows it to be installed or removed under power, even
in hazardous areas.
1.3.4 sWItCh InterfaCe
Universal single-phase current monitoring, single- or 3-phase ground-fault detection, and voltage
monitoring are provided by the Switch Interface (SIS/SIC) module. One device is required for each
control point, and two versions are available: SIS for use with SSRs, and SIC for use with the
contactor. Both units also incorporate a universal power supply, allowing operation directly from
100 Vac to 277 Vac. Use with higher trace voltages is also possible, using a separate power source
or a small step-down transformer.
Redundant operation is supported, allowing a control module to automatically power itself from
either of two switch interface modules or both. This permits one heat-trace circuit to be turned off
for maintenance without affecting the operation of the other circuit.
1.3.5 CommunICatIons InterfaCe
In applications where the user wishes remote configuration capability or wants to communicate
trace information and/or alarms to another device such as the GCC (Group Communications
Controller), an optional communications interface may be installed in the control module.
A modem version that maintains compatibility with legacy products is available, or other industry-
standard interfaces such as RS-232 and RS-485 may be specified.
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