A52x Series Electronic Refrigeration Controller with Adaptive Defrost Technical Bulletin
5
Figure 4: A52x Controller High Voltage Terminal Block Connections
Refrigeration Mode
Refrigeration mode is the normal operating mode of the A52x Controller. The system cycles the compressor on and
off, and operates the evaporator fans according to the setup selections to maintain the set point temperature in the
refrigerated space. See Figure 5 on page 6 for a common application of the A52x Controller. The controller exhibits
the following behaviors in refrigeration mode:
Table 3: A52x Controller High Voltage Terminal Blocks, Terminals, and Wire Sizes
Terminal
Block Label
Terminal
Voltages
Description, Function, and Requirements
Recommended
Wire Sizes
90-240 VAC
L1
Two terminals for supply power connection to the A525 Controller.
Requires 90 to 240 VAC; 15 VA, (0.25 A maximum).
0.75 to 2.50 mm
2
(18 to 14 AWG)
L2/N
GND
Earth ground connection terminal.
Compressor
Two terminals for line-voltage, single-pole, single-throw (SPST), dry-
contact relay to the control compressor.
1.50 to 6.0 mm
2
(16 to 10 AWG)
Alarm
L1/LC
The common (LC), normally-open (LNO), and normally-closed (LNC)
terminals for line-voltage, single-pole, double-throw (SPDT), dry-contact
relay to control the user-supplied alarm devices.
0.30 to 2.50 mm
2
(22 to 14 AWG)
LNC
L2/N/LNO
LO-SPD AUX
The A525 Controller includes two terminals for line-voltage, SPST, dry-
contact relay to control an auxiliary device such as a user-provided
alarm device or the low-speed on two-speed evaporator fans. The A524
Controller does not include this relay and terminal block.
0.30 to 2.50 mm
2
(22 to 14 AWG)
HI-SPD
Two terminals for line-voltage, SPST, dry-contact relay to control single-
speed evaporator fans or the high-speed on two-speed evaporator fans.
0.75 to 2.50 mm
2
(18 to 14 AWG)
Defrost
Two terminals for line-voltage, SPST, dry-contact relay to control
resistive defrost heater or bypass defrost solenoid.
1.5 to 6.0 mm
2
(16
to 10 AWG)
HVBIN
Two line-voltage binary input terminals for use with the line-voltage
defrost temperature termination switch. These terminals require an
external power source to provide 120 to 240 VAC, 50/60 Hz activation
power when the external, user-supplied defrost termination switch
closes.
0.30 to 1.50 mm
2
(22 to 16 AWG)
