Sub-Zero SZ-7552-P User manual

Amongst others features, an important one is that
Incase one compressor is not capable of handling the
load, the second compressor will activate and both
compressors will cutout at the lowest set point.
SZ-7552 is two compressor controller with separate
setpoints, differentials and time delays for each
compressor.
The controller features cycling of compressors so that
there is no overload on one compressor.
They are specifically designed for air conditioning
applications wherein the compressor cuts off at setpoint
and is restarted at a temperature of setpoint plus
differential.
Instruction for SZ-7552-P
General Description
1
2
INDEX
4
Parameter
Setting
Press and hold
PRG(prg) key
for 2 seconds.
prg
Display will show ‘P2’ and flash.
To go to other parameters. Use
UP / DOWN keys.
3
Set Point Function : To set the cutout point
of the controller.
Press & hold
SET key for 2
Seconds.
R1 will flash along with respective
setpoint1 for compressor 1.
The setpoint1 value can now be
changed by using the UP/DOWN
keys. After achieving the desired
value, press the set key and
you will see “- - -” which confirms
that the set point has been stored
in memory.
R2 will flash along with
respective set point 2 for
compressor 2. In the similar
manner use UP/DOWN key to
set the desired value and press
set key to confirm the settings.
Display will change to set point 1
and flash
Set Point 1 & 2
Min Max Fac
O
1.0 C
Set Point 1 & 2
Min Max Fac
O
1 C
O
P2-1 C
rS = 0
rS = 1
rS = Resolution
Set Parameter
P3
O
+1.0 C
P2
O
-1.0 C
O
P3+1 C
SZ-7552-P
www.pvrcontrols.com
INDIA
OPERATING
INSTRUCTIONS
DescriptionParameter Page
Set Point1 and set point 2.
To Set other parameters.
Controller for heating or cooling.
Max. High Temp Limit.
Min. Low Temp. Limit.
Differential.
Probe Calibration.
Time Delay.
To Start 2nd Comp. incase 1st Comp.
Min. Off time between two Comp.
Avoid over loading of Comp.
Keypad Lock.
Relay status on Probe Failure.
To set controller Resolution.
Factory set parameter.
End Programming.
Operating messages.
Technical data.
Suggested Wiring diagram.
Panel cutout & Dimensions.
P1
P2
P3
P4
P5
P6
t2
t3
t4
LP
E1
rS
FS
EP
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22-23

10
R1 & time delay of setpoint 1
will flash. Use UP/DOWN keys to set
desired value. Once desired value is
achieved, press set key and you will
see “- - -” which confirms time delay for
set point 1 has been stored in memory.
After pressing UP key R2 flashes
alongwith the time delay for setpoint 2.
Use UP/DOWN keys to set desired,
value.Once desired value is
achieved, press set key and you will
see “- - -” which confirms time delay for
set point 2 has been stored in memory.
To prevent both compressors from
switching on together, there is an
internal 10 second time delay
between simultaneous startups
to prevent an electrical surge.
Function : Set time delay between relay
restart time for comp1 and comp2.
To change
P6 parameter,
press the
SET key.
Time delay R1
Time delay R2
P6
Parameter
Fac.
3 Min
Max
20 Min
Min
0 Min
Fac.
3 Min
Max
20 Min
Min
0 Min
R1
R2
8
P4
Parameter
Once in this mode, R1 and
differential of setpoint 1 will flash.
use UP/DOWN keys to set desired
value. Once desired value is achieved,
press set key and you will see “- - -” this
confirms differential for set point 1 has
been stored.
After up key is pressed
R2 flashes alongwith the differential
for set point 2. Use UP/DOWN keys to
set desired value. Once value is
achieved, press set key. This confirms
differential for setpoint 2.
0
Example : If setpoint 1 is set at 10.0 C.
and differential for setpoint 1 is set
0
at 2.0 C, then when the system
0
reaches 10.0 C, the relay for
compressor 1 will cutout and since
O
the differential is 2.0 C the relay will
O
cutin(restart) at 12.0 C (10.0+2.0).
Function: To set the differential of
set point 1 and set point 2
To change
P4 parameter,
press the
SET key.
Differential 1 & 2
Differential 1 & 2
Max Fac.
0
20.0 C
0
0.5 C
Min
0
2.0 C
Max Fac.
0
20 C
0
1 C
Min
0
2 C
rS = 0
rS = 1
rS = Resolution
Set Parameter
9
Use UP/DOWN keys to set
desired value. In time it may be
possible that the display may be
offset by a degree or so.
To compensate for this error. you
may need to add or minus the degree
required to achieve the correct
temperature. Setting value is from
O O
-10.0 C to + 10.0 C.
Example : The temperature on the
O
display is 28.0 C, whereas the actual
O
temperature is 30.0 C. You will need
to set the P5 mode to 2.0, which
mean that once out of the
programming mode, the display
O
will show temperature 30.0 C
O O
(28.0 C + 2.0 C).
To change
P5 parameter
press the
SET key.
Function : To set probe calibration.P5
Parameter
Max Fac.
0
10.0 C
0
-9.0 C
Min
0
0.0 C
rS = 0
Max Fac.
0
10 C
0
-9 C
Min
0
0 C
rS = 1
rS = Resolution
Set Parameter
6
Function : To set maximum
allowable high temperature limit.
To change
P2 parameter,
Press the
SET key.
Use UP/DOWN key to set
desired value. Once set at a
particular value, this will not
allow both set points to go above
this value.
Example : Setting this parameter
0
at 30.0 C will not allow both set
0
points to go above 30.0 C. Also if
0
the temperature reaches 30.0 C, the
display will show Ht (High
Temperature), indicating that the
temperature has reached or gone
above the value in this
parameter.
XX = Highest Set Point
(Message on Display)
P2
Parameter
Max
Max
Fac.
Fac.
0
50.0 C
0
50 C
Min
Min
0
XX+1 C
0
50.0 C
0
50 C
rS = 0
rS = 1
rS = Resolution
Set Parameter
XX
0
+1.0 C
7
To change
P3 parameter,
press the
SET key.
Use UP/DOWN key to set
desired value. Once set at a
particular value, this will not
allow both set points to go below
this value.
Example : Setting this parameter
0
at 10.0 C will not allow both set
0
points to go below 10.0 C. Also if
0
the temperature reaches 10.0 C, the
display will show Lt (Low
Temperature), indicating that the
temperature has reached or gone
below the value in this
parameter.
Function : To set minimum
allowable low temperature limit.
(Message on Display)
P3
Parameter
XX = Lowest Set Point
0
0.0 C
0
0.0 C
Max Fac.Min
rS = 0
0
XX-1 C
Max Fac.
0
0 C
0
0 C
Min
rS = 1
rS = Resolution
Set Parameter
XX
0
-1.0 C
5
P1 Parameter
Function: To set controller for heating
or cooling.
0 1 0
To change
the P1
parameter,
press the
SET key.
Use UP/DOWN keys to get
desired value & press set
to confirm.
0: Cooling mode and
1: Heating mode.
Min Max Fac.
NOTE : T2 parameter is activated
only when P1=0 (cooling).

12
This mode is used to set the time
delay between the switching off
of both compressors so that they
do not switch off simultaneously.
Example : If this mode is set to
3 seconds the second compressor
will switch off after a minimum
of 3 seconds from the first
compressor switching off.
If set to 0, this feature will not
activate.
Function : To set minimum off
time between two compressor.
To change
t3 parameter,
press the
SET key.
t3
Parameter
Max Fac.
5 Sec
15 Sec
Min
0 Sec
13
To change
t4 parameter,
press the
SET key.
This function is used to avoid
overloading of any one compressor
working at a stretch over a period of
time.
Example : If this parameter is set at
2 hours, the setpoint, differential &
time delay of both compressors will
interchange after 2 hours The
interchange will occur every 2 hours.
Time calculation will start at power on.
This helps by not overworking any
one compressor for long hours and
increases compressor life. If for any
reason the setpoints have been
changed, the time calculation will
start from the last change in these
parameters.
Function : To avoid overloading of
either compressor.
t4
Parameter
Max Fac.
0 Hr
12 Hrs
Min
0 Hr
15
When display
shows E1 press
SET key.
Use UP/DOWN keys to set
desired value.
0 = Both the relays will
stay on with initial start-up
delay of 2 minutes.
1 = Both compressor
performs a duty cycle of
10 minutes ON and
4 minutes OFF.
2 = Both relay will stay OFF.
Function : Relay status on probe
failure.
E1
Parameter
Max Fac.
1
2
Min
0
14
LP
Parameter
Function: To Lock keypad.
To change
LP parameter,
press the
SET key.
Use UP/DOWN keys to set desired
value. This parameter can lock the
keypad so that tampering is not
possible by by-standards.
0 = Keypad unlocked.
1 = Keypad locked.
When locked all parameters can
only be viewed, but not modified.
Max Fac.
0
1
Min
0
16
rS
Parameter
Function: To set controller Resolution.
To change
rS parameter
press the
SET key.
Use UP/DOWN keys to set desired
value.
1 = Controller Resolution will
O
set 0.1 C.
0 = Controller Resolution will
O
set 1 C.
Max Fac.
0
1
Min
0
11
If set to 0, this feature will not activate.
Example : If setpoint 1 is 23 and
setpoint 2 is 25 and if t2 para is set to 7
minutes, if the second comp. cuts out
at 25, if comp. 1 is not able to achieve
23 for a period of 7 minutes, then after
7 minutes, second compressor will
also come on and both compressors
will cutout at the lower setpoint.
This function is used to switch on
the second compressor incase
the heat load cannot be met with
one compressor functioning.
If t2 is set less than P6, then P6 para
will override t2 parameter.
Function : To start second comp. incase
comp 1 cannot achieve the lower set
point.
To change
t2 parameter,
press the
SET key.
t2
Parameter
Fac.
0 Min
Max
30 Min
Min
0 Min
NOTE : T2 parameter is activated
only when P1=0 (cooling).

20
Depth : 71 mm ( W/o back lid).
Connections : Screw terminal blocks.
0 0
Storage temp : -20 C to 70 C (non-condensing).
Input : NTC probe SZ-N75.
≤ 2.5sq mm one wire/terminal only.
00
Probe tolerance at 25 C: +/-0.3 C.
Mounting : Flush panel mounting with fastners.
0 0
Operating temp. : 5 C to 50 C (Non Condensing).
0 0
0 C to 50 C (rS = 1).
Dimensions : Front :75 x 34.5 mm
Power Input : 230 Vac +/-15%, 50Hz, (Other on request).
Housing : Black ABS Plastic, Auto-extinguish.
0 0
Resolution : 0.1 C/1 C.
Frolnt Cover : Polycarbonate plastic.
Panel Cutout : 29 X 71mm.
Display : 3X14.2mm (0.56”) LED.
Front Protection : Front panel is water proof & Ip65 rated.
0 0
Range : 0.0 C to 50.0 C (rS = 0).
Data storage : Non-volatile EEPROM memory.
Compressor Relay : 2 SPDT Relay, 8(2)A/250Vac.
0
Accuracy : +/-1 C.
Technical Data
21
Compressoror Contactor
8(2)A max
Suggested Wiring Diagram
Caution : Wiring for 230Vac Loads Only.
COMP. 1 COMP. 2
230V PROBE
18
Once the set key is pressed, the
controller goes into the normal
mode and displays the temperature
and all settings are recorded.
To end the
programming
press the
SET key.
Function : To set Programming.EP
Parameter
19
Temperature equal to or below the
minimum limit of the set point.
Probe short circuit, circuit open or without
0 0
probe, or temperature >50.0 C or <0.0 C
0 0
when rS = 0 and temperature >50 C or <0 C
when rS=1.
PP
Operating messages and Icon status
Temperature equal to or above the
maximum limit of the set point.
Description
Message
Parameter
P2
P3
Ht
Lt
Compressor 2 relay ON/OFF
Keypad locked/unlocked LP
On/Off
Set Point 2,
P4
ON/OFF
R2
Compressor 1 relay ON/OFF. Set Point 1,
P4
ON/OFF
R1
Time delay in progress Compressor1.
Time delay in progress Compressor2. P6
Flashing
R1
R2
17
To change
FS parameter
press the
SET key.
When set to 1 all parameters are
programmed to factory values.
Useful to debug setting related
problems.
Function : To restore the default
settings of the controller.
FS
Parameter
Max Fac.
0
1
Min
0
22
GASKET
PANEL Side Lock
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26
Disclaimer : This manual & its contents remain the sole property of
PVR CONTROLS, India and shall not be reproduced or distributed
without authorization. Although great care has been taken in the
preparation of this document, the company or its vendors in no
event will be liable for direct, indirect, special, incidental or
consequential damage arising out of the use or inability to use the
product or documentation, even if advised of the possibility of such
damages. No part of this manual may be reproduced or transmitted
in any form or by any means without the prior written permission of
the company. PVR CONTROLS, reserves the right to make and
changes or improvements without prior notice.
Warranty : This product is warranted against defects in
materials and workmanship for a period of one year from the
date of purchase. During the warranty period, product
determined by us to be defective in form or function will be
repaired or, at our option, replaced at no charge. This warranty
does not apply if the product has been damaged by accident,
abuse, and misuse or as a result of service or modification other
than by the company. This warranty is in lieu of any other
warranty expressed or implied. In no event shall the company be
held liable for incidental or consequential damages, including
lost revenue or lost business opportunity arising from the
purchase of this product..
CAUTION
is done by qualified personnel only.
WIRING : The probe and its corresponding wires should never
be installed in a conduit next to control or power supply lines.
The electrical wiring should be done as shown in the diagram.
The power supply circuit should be connected to a protection
switch. The terminals admit wires of upto 2.5sq mm.
WARNING : Improper wiring may cause irreparable damage
and personal injury. Kindly ensure that wiring
Maintenance : Cleaning: Clean the surface of the controller
with a soft moist cloth. Do not use abrasive detergents, petrol,
alcohol or solvents.
Notice : The information in this document is subject to change
in order to improve reliability , design or function without prior
notice and does not represent a commitment on the part of the
company. In no event will the company be liable for direct,
indirect, special, incidental or consequential damage arising out
of the use or inability to use the product or documentation, even
if advised of the possibility of such damages. No part of this
manual may be reproduced or transmitted in any form or by any
means without the prior written permission of the company.
25
Installation : Fixing and dimensions of panel models:
To fix the unit, slide the fastener 1 through the guides 2
as per the position shown in the figure. Move the fastener in
the direction of the arrow, pressing tab 3 it permits to move
the fastener in the opposite direction of the arrow. Once the
controller has been connected, they should be covered with
the lid 4 Silicon sealant should be applied along the
perimeter of the panel cut out or a rubber ‘O’ ring supplied
before the unit is fitted to obtain IP65 grade.
Controller : Controller should be installed in a place
protected by vibration, water and corrosive gasses and
where ambient temperature does not exceed the values
specified in the technical data.
Probe : To give a correct reading, the probe must be
installed in a place protected from thermal influences, which
may affect the temperature to be controlled.
24
23
SZ-7552-P
prg
SET
3
1
42
34.5mm
71mm
19mm
10mm
MAX
71mm
29mm
Panel cutout