8
–40°F to 140°F (–40°C to 60°C) Operation
Extended temperature operation permits installation in all but the harshest environments.
SSR
output modules are limited to operating ambient temperatures of 104°F (40°C) without derating.
Single or Dual Temperature Sensor Inputs
The ability to use one or two temperature sensor (
TS) inputs for each control point allows the
selection of one of eleven control modes and programming of all temperature parameters.
High and Low Temperature Alarms
High and low temperature alarms are offered for both inputs of each control point.
High and Low Current Alarms
Low current alarm is more than just a continuity level alarm. The 920 offers full adjustment over
the entire current measurement range for both high and low current alarm limits.
Solid State or Contactor Output
The 920 is available with externally-mounted solid-state relay (
SSR) output switches or contac-
tors. With the SSR option, the user may select a time-proportional control algorithm, a simple
deadband mode, or one of two ambient control algorithms. The contactor versions always use
either the deadband mode or the proportional ambient contactor mode. Switching device failure
alarms are supported for both types of output devices.
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 cir-
cuit 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 elim-
inates 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.
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