OPERATING

INSTRUCTIONS

INDIA
www.pvrcontrols.com
SZ-7552-P

INDEX
Parameter Page Description
Instruction for SZ-7552-P Set Point1 and set point 2.
3
General Description 4 To Set other parameters.
SZ-7552 is two compressor controller with separate P1 5 Controller for heating or cooling.
P2 6 Max. High Temp Limit.
setpoints, differentials and time delays for each
P3 7 Min. Low Temp. Limit.
compressor.
P4 8 Differential.
They are specifically designed for air conditioning P5 9 Probe Calibration.
P6 10 Time Delay.
applications wherein the compressor cuts off at setpoint
t2 11 To Start 2nd Comp. incase 1st Comp.
and is restarted at a temperature of setpoint plus
t3 12 Min. Off time between two Comp.
differential. t4 13 Avoid over loading of Comp.
LP 14 Keypad Lock.
The controller features cycling of compressors so that
E1 15 Relay status on Probe Failure.
there is no overload on one compressor.
rS 16 To set controller Resolution.
Amongst others features, an important one is that FS 17 Factory set parameter.
EP 18 End Programming.
Incase one compressor is not capable of handling the
19 Operating messages.
load, the second compressor will activate and both
20 Technical data.
compressors will cutout at the lowest set point. 21 Suggested Wiring diagram.
22-23 Panel cutout & Dimensions.
1

Set Point Function : To set the cutout point Parameter

of the controller. Setting
Press & hold Display will change to set point 1 Press and hold Display will show ‘P2’ and flash.
SET key for 2 and flash PRG(prg) key To go to other parameters. Use
Seconds. for 2 seconds.
UP / DOWN keys.
rS = Resolution R1 will flash along with respective
Set Parameter setpoint1 for compressor 1.
The setpoint1 value can now be
rS = 0
Set Point 1 & 2
changed by using the UP/DOWN
keys. After achieving the desired
Min Max Fac value, press the set key and
you will see “- - -” which confirms
prg
P3 P2 O
+1.0OC -1.0OC 1.0 C that the set point has been stored
in memory.
rS = 1
Set Point 1 & 2 R2 will flash along with
Min Max Fac respective set point 2 for
O O O compressor 2. In the similar
P3+1 C P2-1 C 1C manner use UP/DOWN key to
set the desired value and press
set key to confirm the settings.

3 4
 P1 Parameter Function: To set controller for heating P2 Function : To set maximum
or cooling. Parameter allowable high temperature limit.
To change Use UP/DOWN keys to get To change Use UP/DOWN key to set
the P1 desired value & press set P2 parameter, desired value. Once set at a
parameter, to confirm. Press the particular value, this will not
press the 0: Cooling mode and SET key. allow both set points to go above
SET key. 1: Heating mode. rS = Resolution
this value.
Set Parameter
NOTE : T2 parameter is activated rS = 0 Example : Setting this parameter
Min Max Fac. only when P1=0 (cooling). at 30.00C will not allow both set
Min Max Fac. points to go above 30.00C. Also if
0 1 0 the temperature reaches 30.00C, the
XX 0 0
+1.00C 50.0 C 50.0 C display will show Ht (High
Temperature), indicating that the
rS = 1 temperature has reached or gone
above the value in this
Min Max Fac.
0 0 0
parameter.
XX+1 C 50 C 50 C
XX = Highest Set Point

(Message on Display)
5 6

P3 Function : To set minimum P4 Function: To set the differential of

Parameter allowable low temperature limit. Parameter set point 1 and set point 2
To change Use UP/DOWN key to set To change Once in this mode, R1 and
P3 parameter, desired value. Once set at a P4 parameter, differential of setpoint 1 will flash.
press the particular value, this will not press the use UP/DOWN keys to set desired
SET key. allow both set points to go below SET key. value. Once desired value is achieved,
rS = Resolution this value. press set key and you will see “- - -” this
Set Parameter rS = Resolution confirms differential for set point 1 has
rS = 0 Example : Setting this parameter Set Parameter been stored.
0 rS = 0
Min Max Fac. at 10.0 C will not allow both set
Differential 1 & 2
After up key is pressed
points to go below 10.00C. Also if R2 flashes alongwith the differential
XX 0
Min Max Fac. for set point 2. Use UP/DOWN keys to
0.0 C -1.00C 0.0 C the temperature reaches 10.0 C, the
0 0

display will show Lt (Low 0 0

0.5 C 20.0 C 2.0 C0 set desired value. Once value is
Temperature), indicating that the achieved, press set key. This confirms
rS = 1 differential for setpoint 2.
temperature has reached or gone
Min Max Fac. below the value in this rS = 1 0
Differential 1 & 2 Example : If setpoint 1 is set at 10.0 C.
0 C XX-1 C 0 C parameter.
0 0 0
and differential for setpoint 1 is set
Min Max Fac.
XX = Lowest Set Point 0 0 0
at 2.00C, then when the system
1C 20 C 2C reaches 10.00C, the relay for
compressor 1 will cutout and since
the differential is 2.0OC the relay will
(Message on Display) cutin(restart) at 12.0OC (10.0+2.0).
7 8

P5 Function : To set probe calibration. P6 Function : Set time delay between relay
Parameter Parameter restart time for comp1 and comp2.

To change Use UP/DOWN keys to set To change R1 & time delay of setpoint 1
P5 parameter desired value. In time it may be P6 parameter, will flash. Use UP/DOWN keys to set
press the possible that the display may be press the desired value. Once desired value is
SET key. offset by a degree or so. SET key. achieved, press set key and you will
see “- - -” which confirms time delay for
rS = Resolution To compensate for this error. you set point 1 has been stored in memory.
Set Parameter Time delay R1
may need to add or minus the degree
rS = 0 Min Max Fac. After pressing UP key R2 flashes
required to achieve the correct
Min Max Fac. temperature. Setting value is from 0 Min 20 Min 3 Min alongwith the time delay for setpoint 2.
O O
-9.00C 10.00C 0.00C -10.0 C to + 10.0 C. Use UP/DOWN keys to set desired,
R1 value.Once desired value is
achieved, press set key and you will
Example : The temperature on the see “- - -” which confirms time delay for
rS = 1 Time delay R2 set point 2 has been stored in memory.
display is 28.0OC, whereas the actual
Min Max Fac. temperature is 30.0OC. You will need Min Max Fac.
-90C 100C 00C to set the P5 mode to 2.0, which To prevent both compressors from
0 Min 20 Min 3 Min
mean that once out of the switching on together, there is an
programming mode, the display internal 10 second time delay
will show temperature 30.0OC R2 between simultaneous startups
(28.0OC + 2.0OC). to prevent an electrical surge.

9 10
 t2 Function : To start second comp. incase t3 Function : To set minimum off
Parameter comp 1 cannot achieve the lower set Parameter time between two compressor.
point.
To change This mode is used to set the time
To change This function is used to switch on t3 parameter, delay between the switching off
t2 parameter, the second compressor incase press the of both compressors so that they
press the the heat load cannot be met with SET key. do not switch off simultaneously.
SET key. one compressor functioning.
Min Max Fac. Example : If setpoint 1 is 23 and
setpoint 2 is 25 and if t2 para is set to 7
0 Min 30 Min 0 Min Min Max Fac. Example : If this mode is set to
minutes, if the second comp. cuts out 0 Sec 15 Sec 5 Sec 3 seconds the second compressor
at 25, if comp. 1 is not able to achieve will switch off after a minimum
23 for a period of 7 minutes, then after of 3 seconds from the first
7 minutes, second compressor will compressor switching off.
also come on and both compressors
will cutout at the lower setpoint. If set to 0, this feature will not
If t2 is set less than P6, then P6 para activate.
will override t2 parameter.
If set to 0, this feature will not activate.
NOTE : T2 parameter is activated
only when P1=0 (cooling).
11 12

t4 Function : To avoid overloading of LP Function: To Lock keypad.

Parameter either compressor. Parameter
To change This function is used to avoid To change Use UP/DOWN keys to set desired
t4 parameter, overloading of any one compressor LP parameter, value. This parameter can lock the
press the working at a stretch over a period of press the keypad so that tampering is not
SET key. time. SET key. possible by by-standards.

Min Max Fac. Example : If this parameter is set at

0 Hr 12 Hrs 0 Hr 2 hours, the setpoint, differential &
0 = Keypad unlocked.
time delay of both compressors will
interchange after 2 hours The 1 = Keypad locked.
interchange will occur every 2 hours. Min Max Fac. When locked all parameters can
Time calculation will start at power on. 0 1 0 only be viewed, but not modified.
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.

13 14

E1 Function : Relay status on probe rS Function: To set controller Resolution.

Parameter failure. Parameter
When display Use UP/DOWN keys to set To change Use UP/DOWN keys to set desired
shows E1 press desired value. rS parameter value.
SET key. press the
0 = Both the relays will SET key.
stay on with initial start-up
delay of 2 minutes.

1 = Both compressor Min Max Fac. 0 = Controller Resolution will

performs a duty cycle of 0 1 0 set 0.1OC.
10 minutes ON and 1 = Controller Resolution will
Min Max Fac. 4 minutes OFF. set 1OC.
0 2 1
2 = Both relay will stay OFF.

15 16
 FS Function : To restore the default EP Function : To set Programming.
Parameter settings of the controller. Parameter
To change When set to 1 all parameters are To end the Once the set key is pressed, the
FS parameter programmed to factory values. programming controller goes into the normal
press the press the mode and displays the temperature
SET key. SET key. and all settings are recorded.
Useful to debug setting related
problems.

Min Max Fac.

0 1 0

17 18

Operating messages and Icon status Technical Data

Housing : Black ABS Plastic, Auto-extinguish.
Message Description Parameter Frolnt Cover : Polycarbonate plastic.
Temperature equal to or above the Dimensions : Front :75 x 34.5 mm
Ht maximum limit of the set point. P2 Depth : 71 mm ( W/o back lid).
Temperature equal to or below the Panel Cutout : 29 X 71mm.
Lt minimum limit of the set point. P3 Mounting : Flush panel mounting with fastners.
Front Protection : Front panel is water proof & Ip65 rated.
Probe short circuit, circuit open or without Connections : Screw terminal blocks.
probe, or temperature >50.00C or <0.00C ≤ 2.5sq mm one wire/terminal only.
PP when rS = 0 and temperature >500C or <00C Display : 3X14.2mm (0.56”) LED.
when rS=1. Data storage : Non-volatile EEPROM memory.
R1 Set Point 1, Power Input : 230 Vac +/-15%, 50Hz, (Other on request).
Compressor 1 relay ON/OFF. Operating temp. : 50C to 500C (Non Condensing).
ON/OFF P4
Storage temp : -200C to 700C (non-condensing).
R2 Set Point 2,
Compressor 2 relay ON/OFF Compressor Relay : 2 SPDT Relay, 8(2)A/250Vac.
ON/OFF P4
Input : NTC probe SZ-N75.
Keypad locked/unlocked LP Range : 0.00C to 50.00C (rS = 0).
On/Off 00C to 500C (rS = 1).
R1 Time delay in progress Compressor1. Resolution : 0.10C/10C.
P6 Accuracy : +/-10C.
R2 Time delay in progress Compressor2. Probe tolerance at 250C: +/-0.30C.
Flashing

19 20

Suggested Wiring Diagram

230V COMP. 1 COMP. 2
PROBE PANEL Side Lock

GASKET

CONTROLLER
Compressoror Contactor
8(2)A max
Caution : Wiring for 230Vac Loads Only.

21 22
 MAX
10mm Installation : Fixing and dimensions of panel models:
4 2 3 To fix the unit, slide the fastener 1 through the guides 2
1
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
Panel cutout

controller has been connected, they should be covered with

71mm

the lid 4 Silicon sealant should be applied along the

34.5mm
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
19mm 71mm where ambient temperature does not exceed the values
specified in the technical data.
29mm 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.

prg SET

SZ-7552-P

23 24

Disclaimer : This manual & its contents remain the sole property of
CAUTION PVR CONTROLS, India and shall not be reproduced or distributed
WIRING : The probe and its corresponding wires should never without authorization. Although great care has been taken in the
be installed in a conduit next to control or power supply lines. preparation of this document, the company or its vendors in no
The electrical wiring should be done as shown in the diagram. event will be liable for direct, indirect, special, incidental or
The power supply circuit should be connected to a protection consequential damage arising out of the use or inability to use the
switch. The terminals admit wires of upto 2.5sq mm. product or documentation, even if advised of the possibility of such
damages. No part of this manual may be reproduced or transmitted
WARNING : Improper wiring may cause irreparable damage in any form or by any means without the prior written permission of
and personal injury. Kindly ensure that wiring the company. PVR CONTROLS, reserves the right to make and
is done by qualified personnel only. changes or improvements without prior notice.
Maintenance : Cleaning: Clean the surface of the controller Warranty : This product is warranted against defects in
with a soft moist cloth. Do not use abrasive detergents, petrol, materials and workmanship for a period of one year from the
alcohol or solvents. date of purchase. During the warranty period, product
Notice : The information in this document is subject to change determined by us to be defective in form or function will be
in order to improve reliability , design or function without prior repaired or, at our option, replaced at no charge. This warranty
notice and does not represent a commitment on the part of the does not apply if the product has been damaged by accident,
company. In no event will the company be liable for direct, abuse, and misuse or as a result of service or modification other
indirect, special, incidental or consequential damage arising out than by the company. This warranty is in lieu of any other
of the use or inability to use the product or documentation, even warranty expressed or implied. In no event shall the company be
if advised of the possibility of such damages. No part of this held liable for incidental or consequential damages, including
manual may be reproduced or transmitted in any form or by any lost revenue or lost business opportunity arising from the
means without the prior written permission of the company. purchase of this product..

25 26

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