REFRIGERATION AND AIR CONDITIONING Pressure controls, differential controls Type RT
Contents Page Introduction...................................................................................... 3 Features.......................................................................................... 3.................................................................................... 3 Approvals......................................................................................... 3 Materials in contact with the medium.............................................................. 4 Ordering........................................................................................ 4-6 Desing/ Function, controls RT............................................................. 7 Design/ Function, control with deadzone RT L............................................. 8 Design/ Function, differential controls RT................................................. 9 Terminology..................................................................................... 0 Setting........................................................................................... 0 Dimensions and weight.......................................................................... 2 RD5BA502 DKRCC.PD.CB0.A.02-520H434 Danfoss A/S (AC-DSL/mr), 09-2006
Introduction An RT control contains a operated single-pole changeover contact, the position of which depends on the in the in let con nec tion and the set scale value. The RT series includes controls for general applications within in dus tri al and marine refrigeration. The RT series also includes differential controls, controls for neutral zone regulation, and special controls with goldplat ed contact surfaces for PLC ap pli ca tions. Features Waterproof versions Wide regulating range Wide range of units for industrial and marine ap pli ca tions Suitable for alternating and direct current Interchangeable contact system Special versions for PLC applications Cable connection Pg 3.5. Cable diameter 6 4 mm Enclosure IP 66 to EN 60529 / IEC 529, except for versions with ext. reset which are to IP 54. Ambient temperature 50 to +70 C for control housing. Switches See "Ordering, switches". Properties according to EN 60947: Wire dimensions solid/stranded 0.2-2.5 mm 2 flexible, w/out ferrules 0.2-2.5 mm 2 flexible, with ferrules 0.2 -.5 mm 2 Tightening torque max..5 NM Rated impulse voltage 4 kv Pollution degree 3 Short circuit protection, fuse 0 Amp Insulation 400 V IP 54/66 Approvals RT RT A RT AL RT 5A RT 6W, 6B, 6S RT 6AW, 6AB, 6AS RT 30AW, 30AB, 30AS RT 36B, 36S RT 7 RT 7L RT 200 RT 200L RT 260A RT 262A Lloyd s Register of Shipping, UK Germanischer Lloyd, Germany Vd TÜV, Germany Det norske Veritas, Norway Bureau Veritas, France RINA, Registro Italiano Navale, Italy RMRS, Russian Maritime Register of Shipping DIN CERTCO, Germany NKK, Japan Korean Register of Shipping CE marked according to 60947-4, -5 CE marked acc. to PED 97/23/EC category IV, safety equipm. CCC, China Compulsory Certificate Danfoss A/S (AC-DSL/mr), 09-2006 RD5BA502 DKRCC.PD.CB0.A.02-520H434 3
Materials in contact with the medium Type Material W. no. To DIN Comments RT 7, RT 7L RT 200, RT 200L RT A, RT AL RT 5A, RT 5AL RT 260A, RT 262A RT 265A RT RT 6W, 6B, 6S RT 6AW, 6AB, 6AS RT 30AW, 30AB, 30AS RT 36B, 36S Stainless steel 7/7 Brass Brass Plain carbon steel Deep drawing steel Plain carbon steel Case-hardened steel Aluminium Plain carbon steel Deep drawing steel Deep drawing steel Case-hardened steel Free-cutting steel Plain carbon steel Aluminium Stainless steel 7/7 Deep drawing steel STW 22 Free-cutting steel.4306.4568 2.0402 2.032.4306.0338.0402.040 3.0255.4306.0338.4306.0338.4.078.0402 3.0255.4306.4568.0338.4305.0332.078 7224 782 7660 7223 624 652 720 72 7223 624 624 652 65 652 72 7224 624 64 65 Zinc plated, passivated (RT A, RT AL only) Nickel-plated, tinned Zinc plated, passivated Nickel-plated Zinc plated, passivated (RT only) Nickel-plated, tinned Nickel-plated, tinned Nickel-plated Nickel-plated Zinc plated, passivated (RT 6AW, 6AB, 6AS only) (RT 6AW, 6AB, 6AS) Nickel-plated, tinned Nickel-plated Nickel-plated Ordering Pressure controls for fluorinated refrigerants Pressure Low Type RT Regulation range Differential 4 RD5BA502 DKRCC.PD.CB0.A.02-520H434 Danfoss A/S (AC-DSL/mr), 09-2006 Reset Max. working PB Max. test p /4 in. / 6mm flare 0.8 5 0.5.6 aut. 22 25 07-524566 0.8 5 fixed 0.5 man. 22 25 07-524666 G 3/8 A ) RT 200 0.2 6 0.25.2 aut. 22 25 07-523766 High RT 7 0 30 4 aut. 42 47 07-529566 ) BSP ext. thread, ISO 228/. Safety - Pressure controls for R 77 (NH 3 ) and fluorinated refrigerants Pressure Low High Type RT A RT 5A ) BSP ext. thread, ISO 228/. Regulation range Differential Reset Max. working Pressure PB Max. test p Cutting ring 6 mm G 3/8 A ) + weld nipple 6.5/0 mm 0.8 5 0.5.6 aut. 22 25 07-50966 07-50066 0.8 5 fixed 0.5 man. 22 25 07-502766 07-500266 0.8 5.3 2.4 aut. 22 25 07-500766 4 7.2 4 aut. 22 25 07-505266 07-504666 4 7 fixed.2 man. 22 25 07-50666 07-504766
Ordering (continued) *) Meets the requirements in VBG 20 on safety equipment and excess s. W = Wächter ( control). B = Begrenzer ( control S with external reset). = Sicherheitsdruckbegrenzer ( control with internal reset). A rupture in the bellows system of the unit will cause the compressor to stop. Safety controls w EN 2263 / DIN 32733 appr. and CE marked acc. PED, Pres sure Equipment Di rec tive*) Regulation Differential Max. Max. range (fixed) working test Pressure Type Δp Reset /4 in./ G 3/8 A PB p Cutting ring + 6 mm weld nipple 6 mm flare 6.5/0 mm G /2 A ) High RT 36B 2) 0 2.5 max. 0.2 man. 22 25 07-525866 RT 36S 2) 0 2.5 max. 0.2 man. 22 25 07-525966 RT 6W 2) 5 25 2.0-3.0 aut. 34 38 07-50366 High RT 6B 2) 0 28 max..0 man. 34 38 07-503466 RT 6S 2) 0 28 max..0 man. 34 38 07-507566 RT 30AW 3) 0 0.2-0.8 aut. 22 25 07-58766 High RT 30AB 3) 0 max. 0.4 man. 22 25 07-58866 RT 30AS 3) 0 max. 0.4 man. 22 25 07-58966 RT 6AW 3) 5 25 2.0-3.0 aut. 34 38 07-5366 07-503266 High RT 6AB 3 ) 0 28 max..5 man. 34 38 07-53366 07-503566 RT 6AS 3) 0 28 max..5 man. 34 38 07-54666 07-507666 ) BSP ext. thread, ISO 228/. 2) Pressure controls for fluorinated refrigerants. 3) Pressure controls for R 77 (NH3) and fluorinated refrigerants Pressure controls with adjustable dead zone for R 77(NH 3 ) and fluorinated refrigerants Pressure Low High Type RT 260A Type Regulation range Differential Danfoss A/S (AC-DSL/mr), 09-2006 RD5BA502 DKRCC.PD.CB0.A.02-520H434 5 Dead zone NZ Max. working PB Max. test p Cutting ring 6 mm G 3/8 A ) + weld nipple 6.5/0 mm RT AL 2 ) 0.8 5 fixed 0.2 0.2 0.9 22 25 07L00666 07L003366 RT 200L 3 ) 0.2 6 fixed 0.25 0.25 0.7 22 25 07L003266 RT 5AL 2 ) 4 7 fixed 0.35 0.35.4 22 25 07L00766 4) 07L004066 4) RT 7L 3 ) 0 30 fixed.0 3.0 42 47 07L004266 4) ) BSP ext thread, ISO 228/. 2) Pressure controls for (R 77 NH 3) and fluorinated refrigerants 3) Pressure controls for fluorinated refrigerants 4) Without nipple Differential controls for R 77(NH 3 ) and fluorinated refrigerants Regulation range Differential Operating range for LP bellows Max. working PB Max. test p' Cutting ring 6 mm G 3/8 A ) + weld nipple 6.5/0 mm 0.5 4 fixed 0.3 8 22 25 07D00466 07D00266 0.5 4 fixed 0.3 8 22 25 07D002266 2) 0.5 6 fixed 0.5 36 42 47 07D00566 07D002366.5 fixed 0.5 3 42 47 07D00666 07D002466 RT 252A 0..5 fixed 0. 9 22 3 07D00366 07D002566 RT 265A 3 ) 6 fixed 0.5 36 42 47 07D007266 ) BSP ext thread, ISO 228/. 2 ) Man. reset. 3 ) Filter monitor: Alarm = 0.8, cut-out = (factory setting). Differential controls with adjustable dead zone for R 77(NH 3 ) and fluorinated refrigerants Type Regulation range Differential Dead zone NZ Operating range for LP bellows Max. working PB Max. test p G /2 A ) + Weld nipple 6.5/0 mm RT 262 AL 0..5 Fixed 0. 0. 0.33 9 3 07D004366 2) ) BSP ext thread, ISO 228/. 2 ) Differential control for R 77 (NH 3) and fluorinated refrigerants.
Ordering (continued) Special versions RT can be supplied with special switches as follows. When ordering, please state:. Type 2. of standard unit 3. of special switch Switches ) Version Symbol Description Contact load Standard Single-pole changeover switch with termi- Alternating current 2 ) 07-403066 nal board proof against leakage current Ohmic: Fitted in all standard versions of type RT. AC = 0 A, 400 V Snap action changeover contacts. With man. reset For manual reset of unit after contact changeover on rising. For HP units prepared for reset facility. Induktive: AC 3 = 4 A, 400 V AC 5 = 3 A, 400 V Direct current DC 3 = 2 W, 220 V 07-404266 with man. reset With man. reset For manual reset of unit after contact changeover on falling. For LP-units prepared for reset facility. 07-40466 with man. reset With dead zone Standard With dead zone Cuts in two circuits simultaneously Cuts out two circuits simultaneously With nonsnap action changeover contacts Single-pole changover switch with dead zone and terminal board proof against leakage current. Single-pole changeover switch with gold plated (oxide-free) contact surfaces. Increases cut-in reliability on alarm and monitoring systems, etc. Snap action changeover contacts. Terminal board proof against leakage current. Single-pole changeover switch with dead zone and gold plated (oxide-free) contact surfaces. Increases cut-in reliability on alarm and monitoring systems, etc. Snap action changeover contacts. Terminal board proof against leakage current. Single-pole changeover switch that cuts in two circuits simultaneously on rising. Snap action changeover contacts. Terminal board proof against leakage current. Single-pole changeover switch that cuts out two circuits simultaneously on rising. Snap action changeover contacts. Terminal board proof against leakage current. Single-pole changeover switch with non-snap action changeover contacts. Alternating current 2 ) Ohmic: AC = 0 A, 400 V Induktive: AC 3 = 2 A, 400 V AC 5 = A, 400 V Direct current DC 3 = 2 W, 220 V Alternating current 2 ) Ohmic: AC = 0 A, 400 V Induktive: AC 3 = 3 A, 400 V AC 5 = A, 400 V Direct current DC 3 = 2 W, 220 V 3 ) Alternating or direct currnent 25 VA, 24 V ) RT controls meet the conditions of EN 60947-2-9. 2 ) Max. starting current (L.R.) = 7 AC 3. 3 ) If current is led through the contacts 2 and 4, i.e. terminals and 4 con nect ed but not ter mi nal, the max. permissible load is increased by 90 W, 220V. The switches are shown in the position they assume on falling, i.e. after downward movement of the RT main spindle. Available only as a component part of RT controls with adjustable dead zone 07-424066 Available only as a component part of RT controls with adjustable dead zone 07-403466 07-403666 07-0866 The setting pointer of the control shows the scale value at which contact changeover occurs on falling. An exception is RT with switch code no. 07-404266 with Man. re set, where the set ting point er shows the scale value at which con tact changeover occurs on rising pres sure. 6 RD5BA502 DKRCC.PD.CB0.A.02-520H434 Danfoss A/S (AC-DSL/mr), 09-2006
Design Function Pressure control type RT 5. Setting knob 9. Regulation range scale 0. Loop terminal. Pg 3.5 screwed cable entry 2. Main spring 4. Terminals 5. Main spindle 6. Switch 7. Guide bush 8. Contact arm 9. Differential setting nut 23. Bellows element 25. Fixing hole 27. 38. Earth terminal 39. Blow-out disc 44. Pressure setting spindle Key sketch RT control RT control The bellows in the RT control is con nect ed to the low or high pres sure side of the con trol led system via the connection. By turning the setting knob (5) the main spring (2) can be set to balance the in the bel lows. A rise in compresses the bellows and moves the main spindle (5) upwards until spring and bellows are in equilibrium. The main spin dle (5) is fitted with a guide bush (7) and a differential setting nut (9) that together transfer the main spindle move ment to the switch (6). The RT 6W, 6B, 6S, RT 6AW, 6AB, 6AS, RT 30AW, 30AB, 30AS, RT 36B, 36S are equipped with a double bellows (an outer bellows and a reg u lat ing bellows). These units have been tested and approved by TÜV (Technischer Überwachungs Verein, Germany) according to EN 2263 / DIN 32733. W = Wächter ( controls) B = Begrenzer ( controls with external re set) S = Sicherheitsdruckbegrenzer ( controls with internal reset). General for EN 2263 / DIN 327333 approved units. The units are equipped with a double bellows system. When in the plant exceeds the set value, the unit will automatically stop the plant. The double bellows system prevents loss of system charge in the event of bellows rup ture. 2. Versions with designation W or AW cut in again automatically when the has fallen to the set value minus the differential. 3. Versions with designation B or AB are cut in manually with the external re set button. This is possible when the has fallen by a value cor re spond ing to the differential un der the set val ue. 4. Versions with designation S or AS can be cut in manually with the internal reset arm when the pres sure has fallen by a value corresponding to the differential under the set value. As laid down by EN 2263 / DIN 32733 requirements, if a rupture occurs in the reg u lat ing bellows of the unit the refrigerating system compressor will be stopped and can only be restarted when the control has been replaced. A rupture in the outer bellows will cause the cutout of RT 36 to fall 2.5, and the cut-out of RT 6 and RT 30 to fall 4.5 un der the set value. This means that the unit cuts out at normal condensing and thus provides a fail-safe func tion. All RT controls, including those which are EN 2263 / DIN 32733 approved, op er ate independently of changes in the ambient temperature around the control housing. Therefore the set cut-out pres sure and differential are held constant provided the permissible ambient temperatures are not exceeded. Danfoss A/S (AC-DSL/mr), 09-2006 RD5BA502 DKRCC.PD.CB0.A.02-520H434 7
Design Function (continued) Pressure control with dead zone, type RT L 5. Setting knob 9. Regulation range scale. Pg 3.5 screwed cable entry 2. Main spring 5. Main spindle 6. Switch 7. Upper guide bush 8. 8a, 8b. Contact arm 20. Lower guide bush 23. Bellows element 25. Fixing hole 27. 38. Earth terminal 39. Blow-out disc 40. Neutral zone setting nut 44. Pressure setting spindle Key sketch RT L control RT L controls are fitted with a switch (7-4032) with an adjustable neutral zone. This en a bles the units to be used for floating control. The neu tral zone switch contact arms (8a) and (8b) are operated by the spindle guide bushes (7) and (20). RT L control The upper guide bush (7) is Fixed while the low er guide bush (20) can be moved up or down by the setting nut (40). In this way the neu tral zone can be varied between a minimum val ue (equal to the mechanical differential of the unit) and a max i mum value (de pend ing on the type of RT unit). 8 RD5BA502 DKRCC.PD.CB0.A.02-520H434 Danfoss A/S (AC-DSL/mr), 09-2006
Design Function (continued) Differential control, type RT 3. LP connection 4. LP bellows element 5. Setting disc 9. Regulation range scale 0. Coil clamp. Pg 3.5 screwed cable entry 2. Main spring 4. Terminals 5. Main spindle 6. Switch 7. Upper guide bush 8. Contact arm 20. Lower guide bush 24. HP bellows element 25. Fixing hole 34. HP connection 38. Earth terminal 39. Blow-out disc Key sketch RT differential control An RT differential control contains a single-pole changeover switch that makes or breaks depending on the differential between two coun ter act ing bellows elements (LP and HP). Differential controls are used primarily as protection against too low a differential across liquid circulation pumps. A secondary application is the safeguarding of lubricating oil in re frig er a tion compressors. The function of the control is con di tion al only on the differential pres sure, i.e. the difference in between the two counteracting bel lows, whereas it is in de pend ent of the absolute on both bellows. The bellows (4) and (24) are respectively connected to the LP port (lowest ) and the HP port (highest ). The main spring (2) can be set for different differential s by the set ting disc (5). RT differential control If the differential between highest and lowest s falls, the spindle (5) moves down wards and via the upper guide bush (7) actuates the switch contact arm (8). The reverse function occurs if the differential rises. For RT 260A controls used on screw compressors the following applies ). Max. in low bellows condensing = 2. 2. Max. in high bellows lubricating oil = 24. 3. Differential between condensing and lubricating oil must not exceed 3. 4. Pressure change in the low and high pres sure bellows from start to nor mal operation must not exceed 8. ) Since the operating conditions given, are out side the operating range of the unit, the life of the bellows will be reduced to approx. 0 000 op er a tions as against approx. the normal 400 000. Danfoss A/S (AC-DSL/mr), 09-2006 RD5BA502 DKRCC.PD.CB0.A.02-520H434 9
Terminology Floating control A form of delayed control where the correcting element (e.g. valve, damper, or similar) moves towards one extreme position at a rate independent of the magnitude of the error when the error ex ceeds a definite positive value, and to wards the opposite extreme position when the er ror exceeds a definite neg a tive value. Hunting Periodic variations of the controlled variable from the Fixed reference. Neutral zone The interval between the make points of the two contacts. "Snap function" A certain contact force is maintained until irrevocable "snap" is initiated. The time during which the contact force approaches zero is thus limited to a very few milliseconds. Therefore contact bounce cannot occur as a result of, for ex am ple, slight vibrations, before the cut-out point. Contact systems with "Snap function" will change over even when micro-welds are cre at ed be tween the contacts during cut-in. A very high force is cre at ed during cut-out to separate the con tacts. This force immediately shears off all the welds. Thus the cut-out point of the unit remains very accurate and completely independent of the magnitude of the current load. Setting RT with automatic reset - LP The knob is used to set the lowest at which the contact system must be activated (cut-out or cut-in). This value can be read on the main scale of the unit. The differential roller must be used to set the differential. Highest activating = lowest activating pres sure + set differential. RT with manual reset - LP RT controls RT and RT A are obtainable in versions with min. reset. When the pres sure falls to the setting value the con trol cuts out. Manual reset becomes possible when the in the bellows system has risen to a val ue cor re spond ing to the set value + the differential. On falling the follower activates the contact system arm and the con tact changes over. The scale is calibrated so that the scale value cor re sponds to contact changeover on falling pres sure. RT with automatic reset - HP The knob can be used to set the lowest pres sure at which the contact sys tem must be ac ti vat ed (cut-out or cut-in). This value can be read on the main scale of the unit. The differential must be set with the differential roll er. Highest activating pres sure = lowest activating + set differential. RT with manual reset - HP Pressure control RT 5A is obtainable with max. reset. When the has risen to the set value the control cuts out. Manual reset only becomes possible when the pres sure has fallen to a val ue corresponding to the set minus the differential. The differential roller is then used as a follower. On rising the differential roller ac ti vates the contact system arm and the contact changes over. The scale is calibrated so that the scale values cor re spond to contact changeover on rising, which is opposite to RT units with automatic reset. 0 RD5BA502 DKRCC.PD.CB0.A.02-520H434 Danfoss A/S (AC-DSL/mr), 09-2006
Dimensions and weight Weight approx. kg RT control housing RT RT A, AL RT A, AL RT 6A RT 6A RT 6, 36 RT 30A RT 7, 7L, 200, 200L RT 260A RT 262A RT 260A, 262A Danfoss A/S (AC-DSL/mr), 09-2006 RD5BA502 DKRCC.PD.CB0.A.02-520H434