ZX Platform Condensing Unit
12
Fault
Temporary Shutdown/Auto Restart
Lock Out Errors/Manual Restarts
Phase Reversal/ Loss Of Phase
Incorrect 3 Phase Sequence
High Pressure Trip
< 5 Trips In 1 Hour
6th Trip Within 1 Hour
Low Pressure Trip (only on MT Units)
At Every LP Trip
No Lock Out
Discharge Gas Temperature Overheat
< 5 Trips In 1 hour
6th Trip Within 1 Hour
Compressor Over Current
< 5 Trips In 1 Hour
6th Trip Within 1 Hour
Compressor Short Cycling
3 Minutes Between Starts
No Lock Out
Excessive Suction Flood Back
~ 20% Flood Back, Warning Only
No Lock Out
Discharge Sensor Failure (only on LT Units)
< 5 Trips In 1 Hour
6th Trip Within 1 Hour
Other Thermal Sensor Failures
Warning Only
No Lock Out
Table 02
E2 Fault Detection Items
* Compressor Phase Reversal
* Loss of Phase (In 3 Phase Models)
* Compressor Over Current
* Compressor Protector Trip Detection
* Discharge Gas Temperature Over Heat
* High Pressure Cut Out
* Low Pressure Cut Out (MT CDU Only)
* Excessive Refrigerant Flood Back
*Compressor Minimum Off Time
* E2 Sensor Failures
Table 01
Electronic Controller Assembly on a ZX Platform CDU
ZX/ZXL Controller Assembly
ZX platform E2 control offers multiple features which are unique to refrigeration condensing units. E2 real-time control monitors and
optimizes the suction or vapor injection performance to offer efficient performance in ZX MT and LT units. E2 also monitors compressor
operating parameters, so as to protect the system from unsafe operating parameters such as passing through a peak temperature hour
of a peak ambient day; or drop-out of a power-phase; or continued refrigerant loss in the system. E2 controller detects these situations
and, as a first step, will initiate some corrective actions.
For example, when the LT unit experiences an extreme temperature day, E2 control decides to switch from vapor-injection-optimization
to discharge-gas temperature-control to allow the compressor to run safely and pass the extreme weather hours.
Another fault condition which is common in refrigeration systems is compressor overload. If the condenser coils are not cleaned
regularly, the compressor operating discharge pressures rises. This condition is gradual and in conventional CDUs, no advance warning is
provided to the user on this approaching undesirable situation. Ultimately, in such a situation, the internal protector in the compressor
trips. Two problems arise due to internal protector-trip. First: there is no alarm to detect the trip and second: a compressor internal
protector reset may take as long as an hour. This could be critical for the quality of frozen food in freezers or cases. On the other hand,
ZXL E2 controller detects the overload externally and actions a temporary shutdown. E2 Diagnostics will then start transmitting a fault
signal. After multiple attempts, and if the error repeats itself as high as six times within an hour, the E2 will finally shutdown the unit to
avoid expensive compressor failure.
The E2 will activate a buzzer to send an alarm signal at unit-lockout which then requires a manual restart. The buzzer is a standard part of
the ZX platform Gold version CDU . The buzzer can be remotely mounted and has volume and mute capability. The E2 is also designed
to activate an externally connected telephone dialer to send fault notice on a preset telephone number.
ZX platform units are designed to operate under extreme ambient temperatures of up to 48°C. This extremely high-ambient envelope,
combined with the intelligent E2 controller, provides unparalleled benefits to customers.
The E2 control is also designed to apply a ZX defrost (DF) module. The ZX DF module is a basic time initiated DF module and is sup-
plied as an optional accessory. The DF module has two rotary switches by which the user can set up the defrost duration and defrost
interval. The DF module also enables a manual defrost as an override to the rotary switch setting of defrost interval.
The E2 controller consists of two electronic board assemblies: E2 power board and
control board. The power board supplies constant DC power to the E2 control board.
The E2 control board carries the intelligent chip containing the canned programs. The
entire assembly is pre-installed and wired in the factory on a new unit. Both electronic
boards carry a LED light . If the LED lights are on after power-up of the unit, it indicates
normal and proper operation of the electronic boards. Once these lights are on, the
rest of the unit including the compressor is monitored and digital messages are shown
on the diagnostic panel.
Table 01 shows a list of fault detections enabled by E2 controller and diagnostics on ZX
platform CDU. The diagnostics are standard features on the Emerson ZX platform Gold
version.
Table 02 summarizes fault conditions under which the E2 controller initiates “tempo-
raryshutdown—with-auto-restart” and “lock-out trip-condition with- manual-restart.”
