Data Flow Systems TCU800, Installation And Operation Manual

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C h a p t e r 7
Phase Voltage Fault
The TCU’s phase monitor is designed to detect phase losses, high-and low-phase voltage faults and phase sequence faults.
When the TCU detects a phase fault, it disables the pump motor outputs and activates the alarm light and horn relays. The
H-O-A switches can be used to override the TCU’s phase monitor and control the pumps during a phase fault.
If a fault occurs, measure the TCU’s Phase A-B and Phase A-C line-to-line voltages. If a voltage is missing, turn off the
main breaker and check the external phase monitor fuses.
The phase voltage set points establish the range used by the TCU to detect a phase voltage fault. If an erroneous alarm
occurs, check to see that the upper and lower voltage limits are set properly. See Minimum Pump Run and Off Times, Low
& High Phase Voltage Limits: Low- and High-Limit Phase Voltage” in “Chapter 6: Operating Procedures” for instructions
on setting voltage limits.
If the problem cannot be resolved, the TCU may require factory service. See “Appendix H: Support, Service, and Warranty”
for removal, replacement, and servicing instructions.
Motor Starter Fault
A motor starter fault indicates that the TCU’s motor run inputs do not agree with its motor run outputs when the H-O-A
switch is in the “Auto” position. The default time allowed for the input to follow the output is two seconds, but the start
delay and stop delay time intervals can be configured from 2-510 seconds. Zero disables the starter fault alarm, and the
output remains on regardless of the run status input.
To accommodate applications where the run signal may not be immediate, such as soft starts or Run signals from check
valves, you can configure the TCU with a longer start and stop delay.
A pump that experiences a Motor Start Fault (with or without Auto Retry enabled) remains faulted by the TCU (and
the PCU) until the pump sequence is complete (tank or well reaches the Off level set point; no pumps are running in
automatic). The TCU attempts to start the failed pump during the next regular pump cycle. Be aware that the Motor Start
Fault will not clear until the pump actually runs or the H-O-A switch is moved out of Auto.
The TCU requires proper feedback to monitor pump motor run status. If the feedback signal malfunctions, the TCU
activates the Strt alarm. The LED of the faulted pump (located under its H-O-A switch) flashes when a motor starter fault
occurs.
The TCU’s starter relays are solid-state devices with up to 0.1 mA off-state leakage current. This should not cause any
problems with starter coils. However, it may force a solid-state starter with a high-input impedance to energize. If this
occurs, there are two options to try.
• Try connecting a bleed resistor across the solid-state starter input. Select a resistance and wattage to shunt the leakage
current.
• Install isolating relays between the TCU and the solid-state starter. Connect the TCU’s starter relays to the coils of the
isolating relays and control power through the isolating relay contacts to the solidstate starter inputs.