Watlow F4T User Manual

Watlow F4T • 190 • Chapter 5 Function Reference
Off Delay
Set an amount of time the output signal remains on after the Minimum On Time is satisfied
and the signals at A and B indicate the compressor is no longer needed. This prevents the
compressor from turning off prematurely due to a transient condition such as opening a door.
Range: 0 to 9,999 seconds
Note:
During the Off Delay, if either channel's power signal drops below its turn off setting, the
compressor stays on and the Off Delay timer is reset. The timer starts again when A and B
are each above their Turn Off levels.
Time Delay
Set how long the compressor remains on while 0% power is received from the control loops.
This feature turns the compressor off when the power from the control loops is 0% for longer
than the Time Delay setting. Use the Time Delay to distinguish between the case where the
power is 0% because the loop is turned off, and the case where the power is 0% for a short
time when a loop switches from heating to cooling. To ensure the compressor stays on when
needed, but turns off when the control loops are off, set the Time Delay longer than the time
the loop outputs are at 0% in normal operation. If two loops are connected to the Special
Output function block, the Time Delay feature looks for both loops to output 0%. When the
Time Delay is set to 0, this feature is disabled.
Range: 0 to 9,999 seconds
Sequencer
This function coordinates a proportional output and up to three on-off outputs so that a large
amount of power may be controlled proportionally without the expense of a proportional
power control large enough to handle all the power at once.
The sequencer function takes a single input power signal and splits it up into four output
signals. Each output controls a portion of the total output power. The primary output, of-
ten referred to as the vernier output, operates a proportional power controller. The propor-
tional power controller must control the largest portion of the output. The other outputs are
contactors or other on-off power switches.
Signals
Direction
Label Type Function
Receiver
- - - - Analog % Demand for power (0 to 100%)
Transmitters
1 Analog % Proportional output
2 Digital On-off output
3 Digital On-off output
4 Digital On-off output
Function
To operate a proportional power control and up to three on-off power controls as if they were
a single, larger, proportional controller, set Function to Sequencer.

Watlow F4T Specifications

General

Inputs	Thermocouple, RTD, mA, V
Outputs	Relay, SSR, mA, V
Communication	Ethernet, Modbus RTU
Data Logging	Yes
Certifications	CE, UL, cUL, RoHS
Control Modes	PID, On/Off
Power Supply	100 to 240 VAC
Operating Temperature	0 to 50°C
Enclosure Rating	IP65
Display	4.3 in. (109 mm) color touch panel LCD
Control Loops	Up to 4