Danfoss Inverter scroll compressors VZH hybrid manifold VZH Gen3 DSH Application guide

Application guidelines
Inverter scroll compressors
VZH hybrid manifold VZH Gen3+DSH
R410A
http://cc.danfoss.com
Contents
GENERAL INFORMATION ....................................................................................................4
Scope ...................................................................................................................................................................................... 4
Benefits .................................................................................................................................................................................. 4
PRODUCT INFORMATION ...................................................................................................5
System configuration .......................................................................................................................................................5
Tandem .................................................................................................................................................................................. 8
Design pipe .......................................................................................................................................................................... 9
General requirements ...................................................................................................................................................... 9
Suction separator .............................................................................................................................................................11
Oil equalization design .................................................................................................................................................. 11
Design compressor mounting ..........................................................................................12
General requirements ....................................................................................................................................................12
VZH178H Mounting feet ................................................................................................................................................ 12
VZH208H Mounting feet ............................................................................................................................................... 12
VZH257H / VZH278H Mounting feet .........................................................................................................................12
VZH301H Mounting feet ................................................................................................................................................13
VZH410H / VZH465H Mounting feet .........................................................................................................................13
VZH354H Mounting kit .................................................................................................................................................. 13
Design oil level sensor .......................................................................................................14
General requirements ....................................................................................................................................................14
Manage operating envelope .............................................................................................15
Requirement ...................................................................................................................................................................... 15
Manage speed limit ............................................................................................................16
General requirements ....................................................................................................................................................16
Manage superheat .............................................................................................................17
Requirement ...................................................................................................................................................................... 17
System evaluation ...........................................................................................................................................................17
Test, criteria and solutions ............................................................................................................................................ 17
Manage off-cycle migration ..............................................................................................19
Requirement ...................................................................................................................................................................... 19
System evaluation ...........................................................................................................................................................19
Refrigerant charge limit table ..................................................................................................................................... 19
Oil management system for hybrid manifolding ................................................................................................20
Oil management logic ...................................................................................................................................................20
Requirement ......................................................................................................................................................................21
System evaluation ...........................................................................................................................................................21
Test, criteria and solutions ............................................................................................................................................21
Control logic ...................................................................................................................... 22
Safety control logic requirements .............................................................................................................................22
Short cycle protection....................................................................................................................................................22
Defrost logic recommendations ................................................................................................................................23
Pump-down logic recommendations ......................................................................................................................23
Assembly line procedure .................................................................................................. 24
Handling ..............................................................................................................................................................................24
Ordering information .....................................................................................................................................................25
ORDERING INFORMATION .............................................................................................. 25
Compressor ordering codes ........................................................................................................................................25
Accessory ordering codes .............................................................................................................................................25
Accessories ......................................................................................................................... 26
3AB298632269085en-000401

General information

Scope

Benefits
The application guideline describes the operating characteristics, design features and application requirements for hybrid manifolding of the Danfoss DSH fixed-speed compressor and the VZH inverter compressor in air-conditioning and heat pump applications.
To ensure proper parallel installation and running conditions, the following recommendations must be followed:
A parallel compressor installation refers to a system of interconnected compressors with a common suction line and a common discharge line. The technique of mounting compressors in parallel is also called manifolding. The hybrid manifolding in this application guideline refers to the manifolding of the Danfoss inverter compressor (VZH) and fixed speed compressor (DSH), which has several benefits.
• It is essential to respect all the instructions given in these guidelines; please refer to the instruction leaflet supplied with each compressor and the application guidelines for single compressors.
• For additional system components related to specific application requirements, the supplier recommendations must always be respected.
The main reason is reduced operating cost through controlling capacity and power consumption to a greater extent. This is achieved by both staggering the compressor switch-on sequences and regulating the speed of the inverter compressor which allows the parallel system to continuously match its power with the capacity needed.
PRODUCT INFORMATIONSYSTEM DESIGNORDERING INFORMATION GENERAL INFORMATION
Capacity
Compressor n°1
VZH 25-100 rps
A second reason for manifolding the inverter compressor and the fixed speed compressor is improved part-load efficiency. In the variable speed+fixed speed parallel installation, the system can run either only the inverter compressor at lower load or both the inverter and fixed speed compressors at a higher load with the fixed speed compressor operating at 100% load.
Compressor n°1
VZH 25-100 rps
Compressor n°2
xed speed DSH
Therefore, it will be possible to achieve a higher part-load efficiency.
Thirdly, the capacity of the hybrid manifolding system can be widely regulated, for example 10% to 100%. The continuous capacity regulation allows for accurate temperature control and a comfortable indoor environment.
4 AB298632269085en-000401

Oil management concept

System configuration
Hybrid manifolding systems use the dynamic system for oil balance. The suction connections between the two individual compressors are interconnected by a special suction separator design that allows most of oil feed into variable speed compressors.
Discharge line
VZH
VZH
DSH
DSH
An optical-electrical oil level sensor fixed in a variable speed compressor monitors the compressor oil level.
If the oil level drops below the limit, the OEM main controller activates the oil management logic.
Drive
ModBus
OEM main controller
GENERAL INFORMATIONSYSTEM DESIGNORDERING INFORMATION PRODUCT INFORMATION
Oil equalization tube Suction separatorSuction line
Optical oil level sensor
5AB298632269085en-000401
Oil management concept
FS
Return Gas
Oil-rich gas flow
Oil poor gas flow
VS
FS VS
GENERAL INFORMATIONSYSTEM DESIGNORDERING INFORMATION PRODUCT INFORMATION
Downstream compressor
Upstream compressor
The hybrid manifolding system uses the dynamic system for oil balance.
The suction connections of the two individual compressors are interconnected by a suction separator that integrates with the suction oil separator and the gas restrictor. The variable speed compressor (VS) is installed in the upstream position which appears first on suction line and fixed speed compressor (FS) is installed on downstream position.
The oil which clings back along the main suction line is separated by the suction separator which
Suction separator (Oil separator/gas restrictor)
returns most of the oil in the suction gas to the upstream compressor. The suction separator creates a slight pressure drop to ensure lower sump pressure between two compressors are well balance when fixed speed compressor is ON and the inverter compressor is running at maximum speed. When the variable speed compressor runs at any frequency below maximum speed, the sump pressure in the fixed speed compressor is lower than the variable speed compressor, and driven by the sump pressure difference, the excess oil from the variable speed compressor runs into the fixed speed compressor sump.
6 AB298632269085en-000401
Oil management concept
Approved hybrid tandem configurations and capacity range
Different configurations of hybrid tandems are possible. All VZH models (high/low pressure ratio/ different voltage) could be manifolded with fixed speed compressors.
Danfoss VSD : VZH compressor DriveTM 380-480 Volt
Model Description
VZH178 H VZH088+DSH90 68.9 19.6 73.9 21.0 VZH208H VZH088+DSH120 77.7 22.1 83.7 23.8 VZH257H VZH117+DSH140 9 7. 8 27.8 105. 2 29.9 VZH278H VZH117+DSH161 101.6 28.9 110.1 31.3 VZH301H V ZH117+DSH184 106.2 30.2 115 .7 32.9 VZH354H VZH170+DSH18 4 137 39.1 146 41.9 VZ H410H VZH170+DSH240 151.9 43.2 164.9 46.9 VZH465H VZH170+DSH295 164.6 46.8 179. 3 51
TR: Ton of Refrigeration Refrigerant: R410A
Standard rating conditions: ARI standard Evaporating temperature: 7.2°C Superheat: 11.1k
Condensing temperature: 54.4°C Subcooling: 8.3k
Subject to modification without prior notification
Data given for motor code G compressor – for full data details and capacity tables, please refer to Coolselector2
www.coolselector.danfoss.com
FS: 50Hz, VS:100Hz FS: 60Hz, VS: 100Hz
kW TR kW TR
GENERAL INFORMATIONSYSTEM DESIGNORDERING INFORMATION PRODUCT INFORMATION
7AB298632269085en-000401

Dimensions

Tandem

GENERAL INFORMATIONSYSTEM DESIGNORDERING INFORMATION PRODUCT INFORMATION
H H
D
L
Tandem model Composition
VZH178 H VZH088+DSH090
VZH208H VZH088+DSH120
VZH257H VZH117+DSH140
VZH278H VZH117+DSH161
VZH301H VZH117+DSH184
VZH354H VZH170+DSH184
VZ H410H VZH170+DSH240
VZH465H VZH170+DSH295
Tandem configurations are achieved by assembling individual compressors
Outline drawing
number
               
8560156 1" 5/8 1" 3/8 1011 445 482
8560155 1" 5/8 1" 3/8 811 445 482
8560154 1" 5/8 1" 3/8 1011 445 540
8560153 1" 5/8 1" 3/8 811 445 540
8560152 1" 5/8 1" 3/8 1024 445 540
8560151 1" 5/8 1" 3/8 811 445 540
8560152 1" 5/8 1" 3/8 1024 445 540
8560151 1" 5/8 1" 3/8 811 445 540
8560150 1" 5/8 1" 3/8 111 6 445 555
8560149 1" 5/8 1" 3/8 811 445 555
856014 8 2" 1/8 1" 5/8 1241 583 682
8560147 2" 1/8 1" 5/8 890 583 682
8556271 2" 1/8 1" 5/8 1245 583 682
8556270 2" 1/8 1" 5/8 953 583 682
8556271 2" 1/8 1" 5/8 1245 583 682
8556270 2" 1/8 1" 5/8 953 583 682
D
L
Suction Discharge L (mm) D (mm) H (mm)
8 AB298632269085en-000401

Design pipe

General requirements Proper piping practices should be employed to:

1. Ensure adequate oil return, even under minimum load conditions (fixed speed compressor off, variable speed compressor at minimum speed, minimum evaporating conditions). If minimum refrigerant velocity cannot be reached, it is strongly recommended that an oil separator is used. For a validation test, the see section “Manage oil in the circuit”.
To condenser
0.5% slope
max. 4 m
max. 4 m
4 m/s or more
U-trap, as short as possible
8-12 m/s
Evaporator
0.5% slope
4 m/s or more
2. Prevent condensed liquid refrigerant from draining back into the compressor when stopped (discharge piping upper loop). For validation tests, see the section “Manage off-cycle migration”.
General recommendations are described in the figures below:
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION SYSTEM DESIGN
HP
LP
U trap, as short as possible
Upper loop
HP
LP
3D flexibility
3. Piping should be designed with adequate three-dimensional flexibility to avoid excess vibration. It should not be in contact with the surrounding structure, unless a proper tubing mount has been installed. For more information
Condenser
on noise and vibration, see the section “Sound and vibration management” in the application guideline for Danfoss VZH Gen3 scroll compressors (AB300034185311en).
9AB298632269085en-000401
Design pipe
Suction on left Suction on right
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION SYSTEM DESIGN
Variable speed
Fixed speed
Fixed speed Variable speed Tandem model Suction direction
DSH090 VZH088 V ZH178H Left/Right
DSH120 VZH088 VZH208H Left/Right
DSH140 VZH117 VZH257H Left/Right
DSH161 VZ H117 VZH278H Left/Right
DSH184 V ZH117 VZH301H Left/Right 50 & 60 120Z0656
DSH184 VZH170 VZH354H
DSH240 V ZH170 VZH410H Left/Right 50 & 60 120Z0657
DSH295 V ZH170 VZH465H Left/Right 50 & 60 120Z0655
Note: The tandem accessory includes oil equalization kits and oil level sensor. For compressors that need a UL certificate, please order the accessory kit with the 24V oil level sensor.
+
+
+
+
+
Left
+
Right
+
+
+
Hz of FS
compressor
50 120Z0 676
60 12 0Z0675
50 120Z0664
60 120Z0658
50 120Z0666
60 120Z0665
50 120Z0665
60 120Z 0674
50
60
50
60
Fixed speed
Suction
separator code
120Z0683
120Z0683
120Z0655
120Z0655
120Z0 687
120Z0 687
120Z0 687
120Z0 687
Variable speed
Tandem accessory kit code
120Z0653 (with 24V oil level sensor)
120Z0654 (with 230V oil level sensor)
120Z0653 (with 24V oil level sensor)
120Z0654 (with 230V oil level sensor)
120Z0651 (with 24V oil level sensor)
120Z0652 (with 230V oil level sensor)
120Z0651 (with 24V oil level sensor)
120Z0652 (with 230V oil level sensor)
120Z0653 (with 24V oil level sensor)
120Z0654 (with 230V oil level sensor)
120Z0653 (with 24V oil level sensor)
120Z0654 (with 230V oil level sensor)
120Z0653 (with 24V oil level sensor)
120Z0654 (with 230V oil level sensor)
120Z0653 (with 24V oil level sensor)
120Z0654 (with 230V oil level sensor)
120Z0651 (with 24V oil level sensor)
120Z0652 (with 230V oil level sensor)
120Z0682 (with 24V oil level sensor)
120Z0681 (with 230V oil level sensor)
120Z0682 (with 24V oil level sensor)
120Z0681 (with 230V oil level sensor)
120Z0682 (with 24V oil level sensor)
120Z0681 (with 230V oil level sensor)
120Z0682 (with 24V oil level sensor)
120Z0681 (with 230V oil level sensor)
120Z0649 (with 24V oil level sensor)
120Z0650 (with 230V oil level sensor)
120Z0649 (with 24V oil level sensor)
120Z0650 (with 230V oil level sensor)
+
10 AB298632269085en-000401
Design pipe

Suction separator

Oil equalization design

The suction connections of the two individual compressors are interconnected by a suction separator, which is supplied as an accessory.
The two compressors are connected by a ½" or ¾" oil equalization pipe. To fix the oil equalization connection rotolock, use the adaptor sleeves
½"
Suction separator
and the seal gasket which were included in the tandem accessory kit.
Model: VZH178H-208H-257H-278H-301H/-354H (DSH184 oil equalization line)
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION SYSTEM DESIGN
Tightening torque 100NM
Model: VZH354H-410H-465H (VZH170 oil equalization line)
¾"
Tightening torque 145Nm
Supplied with the compressor Included in tandem kit Not supplied
Supplied with the compressor Included in tandem kit Not supplied
11AB298632269085en-000401

Design compressor mounting

Tightening torque

General requirements

VZH178H Mounting feet

GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION SYSTEM DESIGN

VZH208H Mounting feet

The tandem is fixed to the frame using the flexible grommets that are supplied with
The compressors are fixed to the frame using rubber grommets, mounting sleeves, and washers (supplied with the compressors).
HM 8 bolt
Lock washer
Flat washer
Steel mounting sleeve
Rubber grommet
Nut
Base plate, frame, etc. with sucient rigidity
Mounting for DSH090 and VZH088
15Nm
15 mm
The compressors are fixed to the frame using rubber grommets, mounting sleeves, and washers (supplied with the compressors).
Because VZH088 is 7 mm smaller than DSH120, in order to ensure that the oil equalization
Tightening torque
HM 8 bolt
Lock washer
Flat washer
Steel mounting sleeve
Rubber grommet
15Nm
15 mm
the compressor or which are included in the accessory kit.
connection is at the same level for both compressors, an additional 7mm rigid spacer must be added under VZH088 (see drawing. The 7 mm rigid spacer is supplied with the tandem accessory kit).
Tightening torque 15Nm
Rigid spacer

VZH257H / VZH278H Mounting feet

Nut
Base plate, frame, etc. with sucient rigidity
Mounting for DSH120
The compressors are fixed to the frame using rubber grommets, mounting sleeves, and washers (supplied with the compressors).
Tightening torque
HM 8 bolt
Lock washer
Flat washer
Steel mounting sleeve
Rubber grommet
Nut
Base plate, frame, etc. with sucient rigidity
Mounting feet
15Nm
15 mm
Mounting for VZH088
12 AB298632269085en-000401
Design compressor mounting
Tightening torque 21Nm
28mm
HM8 bolt

VZH301H Mounting feet

VZH410H / VZH465H Mounting feet

The compressors are fixed to the frame using rubber grommets, mounting sleeves, and washers (supplied with the compressors).
Because VZH117 is 7 mm smaller than DSH184, in order to ensure that the oil equalization
Tightening torque
HM 8 bolt
Lock washer
Flat washer
Steel mounting sleeve
Rubber grommet
Nut
Base plate, frame, etc. with sucient rigidity
Mounting for DSH184
15Nm
15 mm
The compressors are fixed to the frame using rubber grommets, mounting sleeves, and washers. The VZH mounting kits are supplied
connection is at the same level for both compressors, an additional 7mm rigid spacer must be added under VZH117 (see drawing. The 7 mm rigid spacer is supplied with the tandem accessory kit).
Tightening torque 15Nm
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION SYSTEM DESIGN
Rigid spacer
Mounting for VZH117
with the VZH compressor, and DSH mounting kits are included in the tandem accessory kit.

VZH354H Mounting kit

Tightening
HM 8 bolt
Lock washer
Flat washer
Steel mounting sleeve
Rubber grommet
Nut
Mounting feet
torque 21Nm
Compressor base plate
28 mm
The compressors are fixed on the frame using rubber grommets, mounting sleeves, washers (delivered with the compressors).
Tightening torque 15Nm
Lock washer
Steel mounting sleeve
Nut
HM8 bolt
Flat washer
Rubber grommet
Rigid spacers
Because DSH184 is 14mm smaller than VZH170, in order to have oil equalization connection at the same level for both compressors, two additional 7mm rigid spacers must be added under DSH184 (See below drawing, two 7mm rigid spacers are provided in Tandem accessory kit).
HM8 bolt
Tightening torque 21Nm
28mm
Base plate, frame, etc. with enough rigidity
Mounting for DSH184 Mounting for VZH170
13AB298632269085en-000401

Design oil level sensor

General requirements Oil level sensor is a special component which

assembles on variable speed compressor. It is
GENERAL INFORMATIONPRODUCT INFORMATIONSYSTEM DESIGNORDERING INFORMATION
GENERAL INFORMATION
VZH088 VZH117 VZH170
provided in oil level sensor accessory kit.
14 AB298632269085en-000401

Manage operating envelope

Requirement The operating envelope for hybrid manifolding is

shown below, and guarantees reliable operation of the compressor for steady-state operation.
VZH088/117 C Operating Map - 575V/400V/208V
75
70
65
60
55
50
45
40
Tc (°C)
35
30
25
20
15
10
5
-35 -30 -25 -20 -15 -10 -5 0 5 1510 30 352520
50-90 rps
50-100 rps
30-90 rps
The steady-state operation envelope is valid for a suction superheat of between 5K and 30K.
30-90 rps
GENERAL INFORMATIONPRODUCT INFORMATIONSYSTEM DESIGNORDERING INFORMATION
25-90 rps
25-100 rps
Te (°C)
VZH170 C Operating Map - 575V/400V/208V
75
70
65
60
55
50
45
40
Tc (°C)
35
30
25
20
15
10
5
-35 -30 -25 -2 0 -15 -10 -5 0 5 1510 30 352520
50-90 rps
50-100 rps
25-100 rps
30-90 rps
30-90 rps
25-90 rps
Te (°C)
Note:
1) The solid line envelope is valid for a suction superheat within 5K (9°F) at nominal voltage. Higher suction superheat may lead to discharge temperatures above 135°C (275°F) For superheat between 5K and 11K, this top left envelope might be reduced by condensing temperature of 1°C or 2°C (1. 6°F to
3.2°F) in order to keep discharge T° below 135°C (275°F) For superheat above 11K (20°F), the envelop will further be reduced based on 135°C (275°F) discharge temperature restriction.
2) For 380V power input, permitted highest condensing temperature will decrease accordingly: 25-100rps, condensing temperature from 60°C to 56°C(140°F to 133°F); 30-90rps, condensing temperature from 68°C to 65°C(154°F to 149°F).
SYSTEM DESIGN
Pressure settings
bar (g) psi (g)
R410A
Working pressure range low side 2. 3~15. 7 33.36~227.7 Maximum high pressure safety switch setting 48.7 706.33 Minimum low pressure safety switch setting 1.5 21.75
Recommended pump-down switch settings
1.5 bar below nominal evaporating pressure
21 psi below nominal
evaporating pressure with
minimum of
Minimum low pressure pump-down switch setting 2.3bar(g) 33 psig
15AB298632269085en-000401

Manage speed limit

General requirements

GENERAL INFORMATIONPRODUCT INFORMATIONSYSTEM DESIGNORDERING INFORMATION GENERAL INFORMATION
Speed limit guarantees compressor reliability and must be respect. Details refer to
single VZH M/L GEN3 guideline”Manage speed limit”
16 AB298632269085en-000401

Manage superheat

Requirement

System evaluation

Basic unit
single exchanger
as evaporator and
condenser
X X Optional Pass liquid flood back test
X - X Recommended
During normal operation, refrigerant enters the compressor as a superheated vapour. Liquid flood back occurs when some of the refrigerant entering the compressor is still in a liquid state.
In the steady-state condition, the expansion device must ensure a suction superheat of between 5k and 30k.
Advance unit Multiple exchangers as evaporator or condenser (heat-recovery, exchanger,
four-pipe chiller…)
X X Mandatory Pass liquid flood back test
X X Mandatory
Liquid flood back can cause oil dilution and, in extreme situations, lead to liquid slugging that can damage compression parts.
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION
Tes t
Non-reversible
Reversible
Suction accumulator
Pass liquid flood back test
Pass defrost test
Pass liquid flood back test
Pass defrost test

Test, criteria and solutions

Tes t No Purpose Test condition Pass criteria Solutions
Liquid flood back testing must be carried out under expansion valve threshold operating conditions:
Variable speed On at min.speed / fixed speed Off
Running conditions corresponding to the lowest foreseeable evaporation, and highest foreseeable condensation
In case of reversible system, the test must be done in both cooling and heating mode If advanced unit, test in all possible configurations
Tests must be carried out in the most unfavourable conditions:
fan staging
compressor ramping up and down
The defrost test must be carried out in the most unfavorable conditions (at 0°C evaporating temperature)
Suction superheat >5k
The oil superheat must not be more than 30 sec below the safe limit defined in the dilution chart (see graph below)
The oil superheat must not be more than 30 sec below the safe limit defined in the dilution chart (see graph below)
1. Check expansion valve selection and setting (EXV) check measurement chain and PID.
2. Add a suction accumulator*
1. In reversible systems, the defrost logic can be worked out to limit the liquid flood back effect. (For more details see “Control logic”)
2. Add a suction accumulator*
Liquid flood back test
Defrost test
Steady-state
Trans ient
Check liquid flood back during defrost cycle
SYSTEM DESIGN
* A suction accumulator offers protection by trapping the liquid refrigerant upstream from the compressor. The accumulator should be sized at least 50% of the total system charge. The suction accumulator dimensions can impact oil return (gas velocity, oil return, hole size etc.), and therefore the oil return has to be checked according to the “Manage oil in the circuit” section.
17AB298632269085en-000401
Manage superheat
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION
The oil temperature sensor must be placed between the oil sight glass and the compressor baseplate for fixed speed compressor, and beside the oil level sensor for the variable speed compressor. Use a little thermal paste to improve conductivity. The sensor must also be thermally insulated correctly from the ambience.
Oil superheat is defined as: (Oil temperature - Evaporating temperature)
VZH088 117 170/R410A
SYSTEM DESIGN
Dilution chart (reference at 20°C / 68°F ambient temperature)
15 14
13 12
Safety area
11 10
9
8 7 6 5
Oil superheat (K)
4
3
Unsafety area Max 60secs per event
2 1
0
-25
-20 -15 -10 0510 15 20 25
Saturated Suction temperature °C
18 AB298632269085en-000401
Manage off-cycle migration
Off-cycle refrigerant migration happens:
when the compressor is located at the coldest part of the installation, and refrigerant vapour then condenses in the compressor, or

Requirement

The amount of liquid refrigerant in the compressors must not exceed the charge limit.

System evaluation

Non split Split Below charge limitAbove charge limit
X X Optional Mandatory Mandatory Optional
X X Mandatory Mandatory Mandatory Recommended
X - - Mandatory Mandatory Mandatory Recommended
*Surface sump heater The surface sump heaters are designed to protect the compressor against off-cycle refrigerant migration. Additional heater power or thermal insulation is needed in case the ambient temperature falls below -5°C and the wind speed is above 5 m/sec. The heater must be turned on whenever all the compressors are off. Surface sump heater accessories are available from Danfoss (see the “Accessories” section).
Surface sump
heater*
directly in the liquid phase as the result of gravity. When the compressor starts running again, the refrigerant diluted in the oil generates poor lubrication conditions. In extreme situations, this leads to liquid slugging that can damage compressor parts.
Non-return valve
Liquid line
solenoid valve**
Pump-down
cycle***
**Liquid line solenoid valve (LLSV) An LLSV is used to isolate the liquid charge on the condenser side, thereby preventing refrigerant being transferred to the compressor during off-cycles. The electronic expansion valve that closes automatically including in power shut down situation can replace the LLSV. The quantity of refrigerant on the low-pressure side of the system can be further reduced by using a pump-down cycle in association with the LLSV.
***Pump-down cycle By decreasing pressure in the sump, pump down:
• evacuates refrigerant from the oil
• sets the sump saturating pressure much lower than the ambient temperature, and as a result, refrigerant condensation is avoided in the compressor. Pump-down switch setting must be set higher than 2.3 bar(g).
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION
SYSTEM DESIGN

Refrigerant charge limit table

For more details on pump-down cycle see the section “Control logic”.
Tandem models Refrigerant charge limit(kg)
VZH178H/VZH208H 8.0
VZH257H/VZH278H/VZH301H 10.0
VZH354H/VZH410H/VZH465H 15. 0
19AB298632269085en-000401

Manage oil in the circuit

Non return valve
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION

Oil management system for hybrid manifolding

Non-return valve at discharge prevents
R
from liquid or gas migration. Selection of non­return valve is a trade-off between pressure dropping at high speed, and the state of the valve stability while at low speed. See Section Prevent off cycle migration §Test and components required per application to know when to use non return valve
The oil management system architecture for hybrid manifolding is described below.
An oil equalization tube between the variable speed compressor and the fixed speed compressor is used to maintain the oil balance.
OEM main controller Drive
ModBus
The following table displays present Danfoss non-return valve selection per each specific compressor. DSH are with internal NRV, no need external NRV.
Compressor model NRV model
VZH088 NRV 16
VZH117 NRV 19
VZH170 NRV 22
An oil level sensor need to be installed on the variable speed compressor. The oil level sensor monitors the compressor oil level and send oil level signal to OEM main controller. When oil level is below the minimal, OEM controller enter in oil management mode to recover a proper oil level in compressor. If oil level cannot be recovered, controller stop the system.
SYSTEM DESIGN

Oil management logic

FS
Power supply
Oil equalization tube
In order to maintain the proper oil level in the compressors, an oil management control logic needs be implemented in the OEM controller.
The oil management control logic must include three steps.
1. In the case of low oil level detection, an oil balance mode (Variable speed on, Fixed speed off) is activated to recover oil from fixed speed to variable speed.
VS
Optical oil level sensor
2. If oil level cannot be recovered in VS compressor, controller go to Oil boost Mode (Variable speed on, Fix Speed on) in order to recover oil trapped in system.
3. If the oil level is still below the limit after a full oil balance action and oil boost action have been completed, the controller must enter in protection mode, and stop the system in alarm.
For more detailed oil management logic, please refer to “Oil management logic” in the annex.
20 AB298632269085en-000401
Manage oil in the circuit

Requirement

Fixed speed compressor: The oil level must
be visible or full in the sight glass when the compressor is running and when all the compressors in the circuit are stopped.
Variable speed compressor: This compressor is equipped with an oil level switch located at the minimum acceptable level. If the oil level drops below this limit, the controller must follow the oil logic (See “Oil management logic” in the annex).
R
Fixed speed compressor oil returned status need be monitored in qualification test by normal OSG on FS compressor or additional oil level switch placed on FS OSG, the OEM should make sure enough oil in FS compressor by test on their own unit.

System evaluation

Basic unit
Single exchanger
as evaporator and
condenser
X - - X Optional Pass tests 1 & 2
- - - - - X Mandatory Pass tests 1, 2 & 3
Advance unit
Multiple exchangers as
evaporator or condenser
(heat-recovery, exchanger,
four-pipe chiller…)
X - - X Recommended Pass tests 1 & 2
Split
Non-reversible
Reversible
Non-split
Oil separator

Test, criteria and solutions

Tes t no. Purpose Test condition Pass criteria Solutions
Variable speed On at minimum speed / Fixed speed Off Running condition corresponds to lowest foreseeable evaporation, and highest foreseeable condensation on the system
Running for 6 hours
For a reversible system, perform the test in both heating and cooling
Oil return
1
2
3
test under minimum mass flow
Check oil management control logic is working
Oil return in split system
modes. If it is an advanced unit, test in all possible configurations
Variable speed On at minimum speed / Fixed speed On Running condition corresponding to lowest foreseeable evaporation, and highest foreseeable condensation on the system
Running for 6 hours
For a reversible system, perform the test in both heating and cooling modes. If it is an advanced unit, test in all possible configurations
Variable speed On at 50 rps for VZH088-117 or 40 rps for VZH170 / Fixed speed On
Running conditions corresponding to the lowest foreseeable evaporation, and the highest foreseeable condensation on the system.
Running for 6 hours
For a reversible system, perform the test in both heating and cooling modes. If it is an advanced unit, test in all possible configurations
Since each installation is unique, tests 1 and 2 cannot fully validate the oil return
The oil level must be checked and adjusted at commissioning
Variable speed: No lack of oil alarm
No more than two oil boost cycles per hour
Variable speed: No lack of oil alarm Fixed speed: Oil visible in sight glass
No more than two oil balance cycles per hour
Fixed speed: Oil visible in sight glass
Fix speed: Oil visible in sight glass
No more than two oil balance cycles per hour
Look for potential oil trap Increase oil boost duration Top up with oil, generally 4% of the total system refrigerant charge (in weight)
Oil separator can be added
Look for potential oil trap Increase oil boost duration Top up with oil, generally 4% of the total system refrigerant charge (in weight). If more than 4% is used, look for a potential oil trap in the system
Oil separator can be added
The oil separator is mandatory Pay special attention to “Piping design” Top-up with oil, generally 4% of the total system refrigerant charge (in weight). If more than 4% is used, look for a potential oil trap in the system
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION
Tes t
SYSTEM DESIGN
21AB298632269085en-000401

Control logic

Safety control logic requirements

Safeties
HP switch
LP safety switch
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION
Electronic module (only for
SH180-240 -295)
See the pressure settings
table in the “Manage
operating envelope section”
Contact M1-M2 opened

Short cycle protection Minimum run time is necessary to ensure proper

oil return to the compressor. A 3 minutes minimum run time is usually recommended but some systems may require more time to establish a proper superheat and a stable oil return. Additionally, compressor must not exceed a maximum of 12 starts per hour. 12 starts per
Tripping conditions Re-start conditions
Value Time Value Time
Manual reset
Immediate, no delay
No by-pass
Conditions back to normal
Switch closed again
Max. 5 auto resets during a
12-hour period, then manual
reset
Max. 5 auto resets during a
12-hour period, then manual
reset
is the maximum number of starts acceptable for a limited period to ensure enough time for oil return after start-up. Short cycle protection can be done either by the drive or the unit controller. The following table describes the parameters to adjust depending on short cycle protection selected
hour must not be considered as an average, this
Drive parameters Description Value Default
Short cycle protection is done by unit controller
28.00 Short cycle protection
Short cycle protection is done in drive; LP (low pressure) protection must be connected to T27 to keep LP protection during minimum running time. Terminal 27 (Par 5.12) must be set to “Coast inverse” If Modbus is used it is not necessary to connect terminal 27, but a “Coasting” command must be sent to be able to stop compressor in case of an alarm during minimum run time
Short cycle protection done in unit controller: (preferred option)
Disable Enable
28.00 Short cycle protection Short cycle protection done by the drive. Enable Enable
28.01 Interval between starts
28.02 Minimum Run time
SYSTEM DESIGN
5.12 Terminal 27 Digital input Designated for the LP switch.
The diagram below demonstrates how the function works: (a) Start signal is given by the unit controller (b) Compressor started (c) Compressor stop requested by the unit controller (d) Stop command is ignored. Stop delay warning (W97). (e) Compressor stops when minimum run time (180s) has elapsed. (f) Start signal is given by the unit controller
Start command is ignored until the timer (300s) has elapsed. Only then, can the compressor start.
The compressor cannot stop until the set time (180s) has elapsed. The timer starts counting following a compressor start. Stop command is ignored. Only a coast (inverse) command can override the time and stop the compressor.
Interval between starts 300sec
(g) Start delay (W96)
(b) Compressor started
(c) Stop signal
(d) Stop delayed (W97)
(e) Compressor Stoped
300 sec 300sec
180 sec 12se c
[2]* Coast
inverse
(h) Compressor start
(g) Start command is ignored (h) Compressor starts after the timer interval between starts (300s) has elapsed. (i) Compressor Coast (stop) This command can override the time minimum run time and stop the compressor immediately.
(a) Start signal
Note: The short cycle protection function is not functional during Hand On control of the frequency converter via the LCP. If selecting Hand On or Off, the two timers will be reset to 0, and not start counting until Auto is pressed and an active start command applied. The counters are not available for display or monitoring.
(f) Star t signal (i) Compressor Coast
Stop inverse
22 AB298632269085en-000401
Control logic

Defrost logic recommendations

Variable speed 1
Fixed speed 2
4WV
EXV
ON
ON
Heating
100%
In reversible systems, the defrost logic can be worked out to limit the effects of liquid flood back by:
1. Running at full load during defrost to share the liquid refrigerant between all the compressors.
The following defrost logic combines both advantages:
Defrost
2. Transferring the liquid refrigerant from one exchanger to the other thanks to pressures.
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION

Pump-down logic recommendations

4 Way Valve (4WV) stays in heating mode.
Defrost start. Stop all compressors
EXV opens to transfer liquid from outdoor
to indoor exchanger thanks to pressure
difference
* EXV opening degree and time have to be set to keep a minimum pressure for 4 way valve moving.
Pump down is initiated prior to shutting down the last compressor on the circuit by de-energizing a liquid line solenoid valve or closing electronic expansion valve. When suction pressure reaches the cut-out pressure, the compressor is stopped.
When the pressures are almost bal-
anced*, 4WV changes to cooling mode
Restart variable speed and fixed speed
Defrost end. Stop all compressors
4 WV stays in cooling mode.
EXV opens to transfer liquid from
indoor to outdoor exchanger thanks
to pressure difference
When pressures are almost balanced*,
change 4WV to heating mode.
Restart variable speed and fixed speed
Two types of pump-down exist:
• One-shot pump down (preferred): When the
last compressor in the circuit stops, the suction presssure is falls by 1.5 bar below the nominal evaporating pressure with a minimum of 2,3 bar(g). Even if the suction pressure increases again, the compressor will not restart.
• Continuous pump-down: Compressor restarts
automatically when the suction pressure increases.
SYSTEM DESIGN
23AB298632269085en-000401

Assembly line procedure

The installation and service procedure for a parallel system are similar to basic single-system installations. The selection of additional system components for parallel installations follows the

Handling Danfoss Commercial Compressors recommends

using the lift and handling devices as shown on the right, and that the following procedure be used to prevent damage:
• There are two lifting rings on each compressor.
GENERAL INFORMATIONPRODUCT INFORMATIONORDERING INFORMATION
Use all four rings.
• Maximum loads authorized per sling and for the hoist hook must not be lower than the weight of the assembly.
• If the tandem unit is already installed as a complete installation, it must never be lifted using the lifting rings on the compressors.
basic system common rules. Please refer to the application guidelines for Danfoss VZH Gen3 scroll compressors (AB300034185311en) for detailed installation and service procedures.
SYSTEM DESIGN
24 AB298632269085en-000401

Ordering information

To build a complete tandem installation, the customer must order two must order 2

Compressor ordering codes

Danfoss VZH and DSH scroll compressors can be ordered in either industrial packs or in single packs. Please refer to the single compressor

Accessory ordering codes

The suction separator and tandem kit can be ordered using the code numbers listed in the table below. The suction separator and
Tandem model
VZH178 H VZH088 DSH090 Left/Right
VZH208H VZH088 DSH120 Left/Right
VZH257H VZH117 DSH140 Left/Right
VZH278H VZH117 DSH161 Left/Right
VZH301H V ZH117 DSH184 Left/Right
VZH354H VZ H170 DSH184
VZ H410H VZH170 DSH240 Left/Right
VZH465H VZH170 DSH295 Left/Right
Variable speed
compressor
Fixed speed compressor
Suction
direction
Left
Right
Suction separator Tandem accessory kit
Hz (FS
compressor)
50 Hz 120Z0676 1
60 Hz 120Z0675 1
50 Hz 120Z0664 1
60 Hz 120Z0658 1
50 Hz 120Z0666 1
60 Hz 120Z0665 1
50 Hz 120Z0665 1
60 Hz 120Z0674 1
50 Hz 120Z0656 1
60 Hz 120Z0656 1
50 Hz
60 Hz 120Z0655 1
50 Hz 120Z 068 7 1
60 Hz 120Z 0687 1
50 Hz 120Z0657 1
60 Hz 120Z0657 1
50 Hz 120Z0655 1
60 Hz 120Z0655 1
Code Pack size
120Z0683
compressors, one suction separator and one tandem accessory kit.
application guideline for compressor ordering information (AB300034185311en for VZH Gen3, AB288965961751en for DSH).
the tandem kit selection should be based on compressor model, frequency of fixed speed compressor and oil level switch voltage.
Voltage of oil
level switch
24V 120Z0653 1
230V 120Z0654 1
24V 120Z0653 1
230V 120Z0654 1
24V 120Z0651 1
230V 120Z0652 1
24V 120Z0651 1
230V 120Z0652 1
24V 120Z0653 1
230V 120Z0654 1
24V 120Z0653 1
230V 120Z0654 1
24V 120Z0653 1
230V 120Z0654 1
24V 120Z0653 1
230V 120Z0654 1
24V 120Z0651 1
230V 120Z0652 1
24V 120Z0651 1
230V 120Z0652 1
1
24V 120Z0 682 1
230V 120Z0681 1
24V 120Z0 682 1
230V 120Z0681 1
24V 120Z0 682 1
230V 120Z0681 1
24V 120Z0 682 1
230V 120Z0681 1
24V 120Z0 649 1
230V 120Z0650 1
24V 120Z0 649 1
230V 120Z0650 1
24V 120Z0 649 1
230V 120Z0650 1
24V 120Z0 649 1
230V 120Z0650 1
Code Pack size
GENERAL INFORMATIONPRODUCT INFORMATIONSYSTEM DESIGN
ORDERING INFORMATION
25AB298632269085en-000401

Accessories

Suction separator
Code no. Description Application Packaging
120Z0655 Hybrid manifold suction separator
120Z0657 Hybrid manifold suction separator VZH410H-50/60Hz right/left suction Single pack 1
120Z0656 Hybrid manifold suction separator VZH301H-50/60Hz right/left suction Single pack 1
120Z0666 Hybrid manifold suction separator VZH257H-50Hz right/left suction Single pack 1
GENERAL INFORMATIONPRODUCT INFORMATIONSYSTEM DESIGN
120Z0665 Hybrid manifold suction separator VZH257H-60Hz VZH278H-50Hz right/left suction Single pack 1
120Z0658 Hybrid manifold suction separator VZH208H-60Hz right/left suction Single pack 1
120Z0 664 Hybrid manifold suction separator VZH208H-50Hz right/left suction Single pack 1
120Z0 674 Hybrid manifold suction separator VZH278H-60Hz right/left suction Single pack 1
120Z0 675 Hybrid manifold suction separator VZH178H-60Hz right/left suction Single pack 1
120Z0 676 Hybrid manifold suction separator VZH178H-50Hz right/left suction Single pack 1
120Z0683 Hybrid manifold suction separator VZH354H-50Hz left suction Single pack 1
120Z0 687 Hybrid manifold suction separator VZH354H-50/60Hz right suction Single pack 1
Tandem accessory kit
Code no. Description Application Packaging Pack size
120Z0653 Oil level sensor 24V AC/DC, sleeves, gaskets
120Z0654 Oil level sensor 230V AC, sleeves, gaskets
120Z0651 Oil level sensor 24V AC/DC, sleeves, gaskets
120Z0652 Oil level sensor 230V AC/DC, sleeves, gaskets
120Z0 649
120Z0650
120Z0 681
120Z0 682
VZH465H-50/60Hz right/left suction
Oil level sensor 24V AC/DC, sleeves, gaskets, grommets, washers, bolts
Oil level sensor 230V AC, sleeves, gaskets, grommets, washers, blots
Oil level sensor 230V AC, sleeves, gaskets, grommets, washers, blots
Oil level sensor 24V AC, sleeves, gaskets, grommets, washers, blots
VZH354H-60Hz left suction
VZH178H -257H-278H
with 24V oil level sensor
VZH178H -257H-278H
with 230V oil level sensor
VZH208 H-301H
with 24V oil level sensor
VZH208 H-301H
with 230V oil level sensor
VZ410H-465H
with 24V oil level sensor
VZ410H-465H
with 230V oil level sensor
VZH354H
with 230V oil level sensor
VZH354H
with 24V oil level sensor
Pack
size
Single pack 1
Single pack 1
Single pack 1
Single pack 1
Single pack 1
Single pack 1
Single pack 1
Single pack 1
Single pack 1
Oil level sensor
Code no. Description Application Packaging Pack size
120Z0 561 Oil level sensor 24V AC/DC VZH088-117-170 manifolding version Single pack 1
120Z0 562 Oil level sensor 230V AC VZH088-117-170 manifolding version Single pack 1
ORDERING INFORMATION
26 AB298632269085en-000401
Accessories
Surface Sump Heater
Code no. Description Application Packaging Pack size
120Z0 388 Surface sump heater, 80W, 24V, CE, UL 120Z0 389 Surface sump heater, 80W, 230V, CE, UL Multipack 8 120Z0 390 Surface sump heater, 80W, 400V, CE, UL Multipack 8 120Z0 391 Surface sump heater, 80W, 460V,CE, UL Multipack 8 120Z0 402 Surface sump heater, 80W, 575V, CE, UL Multipack 8 120Z0 360 Surface sump heater + bottom insulation, 56 W, 24 V, CE, UL 120Z0 376 Surface sump heater + bottom insulation, 56 W, 230 V, CE, UL Multipack 6 120Z0 377 Surface sump heater + bottom insulation, 56 W, 400 V, CE, UL Multipack 6 120Z0378 Surface sump heater + bottom insulation, 56 W, 460 V, CE, UL Multipack 6 120Z0 379 Surface sump heater + bottom insulation, 56 W, 575 V, CE, UL Multipack 6 120Z0 667 48W 24V surface sump heater CE and UL 120Z0 668 48W 230V surface sump heater CE and UL Single pack 1 120Z0669 48W 400V surface sump heater CE and UL Single pack 1 120Z0 670 48W 460V surface sump heater CE and UL Single pack 1 120Z0 671 48W 575V surface sump heater CE and UL Single pack 1 120Z0 388 80W 24V surface sump heater CE and UL Multipack 8 120Z0 389 80W 230V surface sump heater CE and UL Multipack 8 120Z0 390 80W 400V surface sump heater CE and UL Multipack 8 120Z0 391 80W 460V surface sump heater CE and UL Multipack 8 120Z0 402 80W 575V surface sump heater CE and UL Multipack 8 120Z070 3 56W 24V surface sump heater + bottom insulation, CE & UL DSH240-295-381-485 Multipack 6 120Z070 4 56W 230V surface sump heater + bottom insulation, CE & UL DSH240-295-381-485 Multipack 6 120Z070 5 56W 400V surface sump heater + bottom insulation, CE & UL DSH240-295-381-485 Multipack 6 120Z070 6 56W 460V surface sump heater + bottom insulation, CE & UL DSH240-295-381-485 Multipack 6 120Z0707 56W 575V surface sump heater + bottom insulation, CE & UL DSH240-295-381-485 Multipack 6
VZH088-117
VZH170
DSH090 to 184
Multipack 8
Multipack 6
Single pack 1
GENERAL INFORMATIONPRODUCT INFORMATIONSYSTEM DESIGN
Model Configration NRV code
VZH178 H VZH088 + DSH090
VZH208H VZH088 + DSH120
VZH257H VZH117 + DSH140
VZH278H VZH117 + DSH161
VZH301H VZH117 + DSH184
VZH354H VZH170 + DSH184
VZ H410H VZH170 + DSH240
VZH465H VZH170 + DSH295
VZH088 DSH090
NRV16 (020B1059) -
VZH088 DSH120
NRV16 (020B1059) -
VZH117 DSH140
NRV19(020 B1054) -
VZH117 DSH161
NRV19(020 B1054) -
VZH117 DSH184
NRV19(020 B1054) -
VZH170 DSH184
NRV22 (020 -1060) -
VZH170 DSH240
NRV22 (020 -1060) -
VZH170 DSH295
NRV22 (020 -1060) -
ORDERING INFORMATION
27AB298632269085en-000401

Annex

Oil Management logic
1. Oil management for hybrid manifolding system
An oil level sensor needs to be installed on the variable speed compressor. The oil level is permanently monitored by OEM main controller. When oil level is below the minimal, OEM
OEM main controller Drive
ModBus
FS
controller enters in oil management mode to recover a proper oil level in compressor. If oil level cannot be recovered, controller stops the system.
VS
2. Oil management description
2.1 Basic rules
Power supply
Oil equalization tube
Oil management system for hybrid manifolding
This specification describes the control logic to implement in OEM controller. This control logic must be implemented and thoroughly tested by OEM.
The variable speed compressor (VS) is primary and the fixed speed compressor (FS) is Secondary. FS must not run alone.
Optical oil level sensor
As oil balancing logic needs to start / stop compressor as well as increase / decrease speed, make sure expansion device is fast enough to maintain liquid flood back within acceptable limit during those transients (Manage super heat chapter).
28 AB298632269085en-000401
Annex
2S
2.2 Oil management modes
The oil management control logic must include 3 steps.
Less than every
20min (TD2*)
Max 45 sec
(TD1*)
Fix speed ON
Oil
balance
Fix speed OFF
Partial Oil
boos (VS only)
Step 1Step
Normal
operation
Low oil level
>5 sec
Low oil
level
Step 1 (Oil balance or partial oil boost)
In case of low oil level detection by Oil level sensor on VS, there is 2 possible actions according to fix speed state:
• Fix speed is ON: Oil can be trapped in fix speed compressor due to pressure unbalance. Oil balance mode is activated. FS is stopped and VS speed is increased; pressure in VS become lower than FS oil is coming back through oil equalization line.
• Fix speed is OFF: Oil is trapped in the system. Partial oil boost is activated. VS speed is increased to slightly increase refrigerant velocity in the system and recover oil, FS remain OFF
Less than every
45min (TD4*)
Max 5min
(TD3*)
Oil level
not
recovered
Oil
Boost
(FS + VS)
Oil level
not
recovered
than TD2 after last step 1, switch immediately to step 2.
Step 2 (Full oil boost)
If oil level cannot be recovered within defined time, oil is trapped in the system. Full oil boost is activated. (VS speed is increased and fix starts (if not already ON). It considerably increases refrigerant velocity in the system and recovers oil.
TD3 is the maximum time to complete step 2. If oil is not recovered within TD3 switch to step 3. If oil is recovered within TD3 come back to normal operation. TD4 is the minimum interval between two step 2. In case of low oil level detection within a time <TD4, switch to step 3.
Protection
tep 3
TD1 is the maximum time to complete Step 1: If oil is not recovered within TD1, switch to Step 2: If oil is recovered within TD1 come back to normal operation. TD2 is the minimum interval between two step 1. If step 1 is requested in less
Step 3 (Protection)
If oil is still lower than limit after completed step 1 & 2, or if oil level drop within a time <TD4, controller must enter in protection mode, and stop the system in alarm.
Note: TD time is adjustable. Please refer to “Parameter and variable table” in page 31.
29AB298632269085en-000401
Annex
2.3 Steps description
2.3.1 Oil balance Function description
Balance oil from FS compressor to VS Compressor.
Enter condition
Low oil level in VS compressor detected by oil level sensor.
AND
FS compressor is ON
AND
t2>TD2, Interval between two Oil balance / Oil boost is > TD2
Cancel condition
High oil level in VS compressor detected by oil level sensor. OR t1>TD1, Oil balance duration exceed TD1
Control sequence
1. At the initial state, VS and FS compressor are ON.
2. Low oil level detected in VS compressor. Reset and Start t1.
3. FS compressor must stop. VS compressor speed must increase to Fboost.
4. When high oil level detected in VS compressor.
• VS compressor speed must be decreased to
minimal speed Fmin.
• Reset and Start t2
• Reset t1
5 When VS compressor speed reaches FStart, FS compressor must restart.
Max TD1
Oil level signal
VS speed
FS speed
t1
Oil lack
2
Fboost
1
3
Oil balance
from FS to VS
compressor
4
t2
FstartFstart
5
30 AB298632269085en-000401
2.3.2 Partial oil boost Function description
Return oil trapped in the system to compressors by increasing refrigerant mass-flow in the system.
Enter condition
Low oil level in VS compressor detected by oil level sensor.
AND
FS compressor is OFF
AND
t2>TD2, Interval between two Oil balance / Oil boost is > TD2
Cancel condition
High oil level in VS compressor detected by oil level sensor. OR t1>TD1,Partial oil Boost duration exceed TD1
Oil level signal
Control sequence
1 At the initial state, VS compressor is ON and FS
compressor is OFF.
2 Low oil level detected in VS compressor. Reset
and start t1 3 VS compressor speed must increase to Fboost. 4 When high oil level detected in VS compressor
• VS compressor speed must be decreased to the
initial speed (Fstart)
• Reset and start t2
• Reset t1
Max TD1
t1
Oil lack
t2
VS speed
FS speed
2
1
3
Fboost
4
31AB298632269085en-000401
Annex
2.3.3 Oil boost Function description
Return oil trapped in the system to compressors by increasing refrigerant mass-flow in the system.
Enter condition
Low oil level in VS compressor detected by oil level sensor.
AND
(t1>TD1, Oil balance / boost duration t1 > TD1 OR t2<TD2, Interval between two Oil balance / Oil boost is < TD2)
Cancel condition
High oil level in VS compressor detected by oil level sensor. OR t1>TD3, Oil balance / boost duration exceeds Maximum Oil boost duration
Control sequence
1. At initial state, oil level is low .Partial oil boost /Oil balance was not successful or was aborted because minim interval criteria. VS compressor is at FStart and FS compressor is either ON or OFF.
2. VS compressor speed must increase to Fboost, FS compressor must start if not already ON Reset and start t1
3. When High oil level detected in VS compressor.
• VS compressor speed must be decreased to the initial speed (Fstart)
• FS compressor to initial state.
• Reset and start t2
• Reset and start t3
• Reset t1
4. When VS compressor speed reaches FStart, FS
compressor must restart (if was ON before)
Max TD3
t1
2
Oil lack
t2
VS comp
FS comp
1
Fboost
3
FstartFstart
32 AB298632269085en-000401
Annex
24VDC MODEL
24VAC MODEL
24VDC MODEL
2.3.4 Protection
Function description
Stop compressors to prevent short of oil running.
Enter condition
Low oil level in VS compressor detected by oil level sensor.
AND
(t1>TD3, Oil balance / boost duration exceeds
Cancel condition
Manual Reset
Control sequence
Stop FS and VS compressor Reset t1 Reset t2
Reset t3 TD3 OR t3<TD4, Interval between two Oil boost is < TD4)
2.4 Parameter and variable table
Name Tex t Attribute Range Default Unit
Fboost Boost action frequency parameter 25~100 70 Hz
TD1 Maximum oil balance / Partial oil boost duration parameter 10~240 30 second
TD2 Interval minimum between two oil balance / Partial oil boost parameter 10~60 20 minutes
TD3 Maximum boost duration parameter 5~12 5 minutes
TD4 Interval minimum between two oil boost parameter 45~120 45 minutes
t1 Oil balance/ Partial oil boost timer Variable second
t2 Interval between two oil balance / Partial oil boost Variable minutes
t3 Interval between two oil boost Variable minutes
2.5 Sensor Wiring diagram
230VAC MODEL
24VAC MODEL
An TEKLAB LC-XN optical-electrical level sensor is fixed on the inverter compressor. The oil level sensor monitors the compressor oil level and sends oil level signal to an external relay (provided by OEM ). Regarding this oil level signal, a 5±2 seconds delay is recommended to
flowing through load or coil of external relay. For relay, output is open.
- Enough oil: Circuit between 2 and 3 will be closed internally, there will be current flowing through load or coil of external relay. For relay, output is closed
24VDC MODEL
be used to consider the oil level fluctuation which may trigger false alarms.
For customers who needs UL certificates, please order 24V AC/DC sensor.
- Lack of oil: Circuit between 2 and 3 will be opened internally, there will be no current
33AB298632269085en-000401
Danfoss Commercial Compressors
Danfoss Inverter Scrolls
is a worldwide manufacturer of compressors and condensing units for refrigeration and HVAC applications. With a wide range of high quality and innovative products we help your company to find the best possible energy efficient solution that respects the environment and reduces total life cycle costs.
We have 40 years of experience within the development of hermetic compressors which has brought us amongst the global leaders in our business, and positioned us as distinct variable speed technology specialists. Today we operate from engineering and manufacturing facilities spanning across three continents.
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Compressors
Our products can be found in a variety of applications such as rooftops, chillers, residential air conditioners, heatpumps, coldrooms, supermarkets, milk tank cooling and industrial cooling processes.
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Danfoss Commercial Compressors, BP 331, 01603 Trévoux Cedex, France | +334 74 00 28 29
AB298632269085en-000401 © Danfoss | DCS (CC) | 2020.07
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