Pentair 920 Series Installation, Operating And Maintenance Instructions page 7

Ground-fault alarm and trip
Ground-fault (GF) current levels are monitored and displayed in milliamps. The availability of the
actual ground-fault level gives the user the choice of both alarm and trip levels suitable for the
particular installation. Using multiple SSRs or a multipole contactor allows all powered legs of
non-neutral circuits to be switched off under GF conditions.
overcurrent protection
A unique overcurrent protection algorithm greatly reduces the possibility of damage to the circuit
or the controller in the event of a temporary overload while allowing for initially high in-rush
currents (SSR options only).
soft starting
Given the circuit breaker size, the 920 will limit the energy let-through to help prevent nuisance
breaker trips due to cable in-rush. This feature makes the controller particularly attractive for use
with self-regulating cables (SSR options only).
minimum/maximum temperature tracking
The controller maintains the minimum and maximum temperature values seen by the controller
since the last reset of these values. This is helpful in determining causes of temperature alarms.
Latching/non-Latching temperature alarms
User-selectable, non-latching temperature alarms allow the controller to automatically clear the
alarm when the condition no longer exists.
high and Low voltage alarms
Operating at voltages less than design can cause serious loss of heater output. The alarming of
preset voltage deviations ensures availability of sufficient wattage output.
power Limiting
The 920 will control the maximum output wattage if the full load power exceeds the specified
maximum power setpoint. This feature eliminates the need for low voltage transformers in many
applications and can assist in standardization of heating cable types (SSR options only).
autocycling
The controller will energize the circuit for 10 seconds at a programmable interval. Circuit alarms
will be generated at the time of autocycle instead of when the heat is required. This feature
eliminates the need for a preventive maintenance program as these tests are performed at regular
intervals by the controller.
temperature sensor failure alarm
Both open and shorted sensors are detected and alarmed by the controller.
random start
A startup delay between 0 and 9 seconds ensures that all units do not come on line at the same
time.
full digital Communications
An optional internal communications interface allows the communication of alarms and analog
data to a monitoring system. Industry-standard RS-232 or RS-485 serial communications are
available for applications requiring direct interfacing to other devices. The modem version
maintains compatibility with legacy products including the GCC-9000/780 Series (Group
Communications Controller). With the availability of the heat trace data at the user's fingertips,
historical trending of temperatures, power consumption, or other parameters are available for
analysis and system optimization.
INDUSTRIAL HEAT TRACING SOLUTIONS EN- Raychem920series-IM-H56874 05/15 7 / 82