Catalogue RK.00.H5.02 317 Danfoss 9/96 Thermostats type KP Introduction KP thermostats are temperature-controlled electrical switches. A KP thermostat has a single pole (SPDT) changeover switch. The position of the switch depends on the thermostat setting and the bulb temperature. A KP thermostat can be directly connected to single-phase a.c. motors of up to about 2 kW, or installed in the control current circuit of d.c. motors and large a.c. motors. • Wide regulating range • Can be used for deep freeze, refrigeration and air conditioning plant • Welded bellows elements mean increased reliability • Small dimensions Easy to install in refrigerated counters or cold rooms. • Ultra-short bounce times Long operating life. Unnecessary cut-in and cut-out of control equipment is avoided. Features • Standard versions with changeover switch Possible to obtain opposite switch function or to connect a signal. • Electrical connection at the front of the unit Facilitates rack mounting. Saves space. • Suitable for alternating and direct current • Cable entry of soft thermoplastics for cables from 6 to 14 mm diameter. • Extensive and wide range Approvals M DEMKO, Denmark O NEMKO, Norway W FIMKO, Finland F Germanischer Lloyd, Germany DSRK, Deutsche-Schiffs-Revision und -Klassifikation, Germany P Polski Rejestr Statków, Poland DnV, Det norske Veritas, Norway RINA, Registro Italiano Navale, Italy BV, France LR, UK MRS, Maritime Register of Shipping, Russia EZU, Czech Republic / Slovak Republic CE according to EN 60730-2-1 to -9 Versions with UL and CSA approvals can be supplied to special order.
Transcript
Catalogue RK.00.H5.02 317 Danfoss 9/96
Thermostatstype KP
Introduction KP thermostats are temperature-controlledelectrical switches. A KP thermostat has a singlepole (SPDT) changeover switch.
The position of the switch depends on thethermostat setting and the bulb temperature.
A KP thermostat can be directly connected tosingle-phase a.c. motors of up to about 2 kW,or installed in the control current circuit of d.c.motors and large a.c. motors.
• Wide regulating range
• Can be used for deep freeze, refrigerationand air conditioning plant
• Welded bellows elements meanincreased reliability
• Small dimensionsEasy to install in refrigerated countersor cold rooms.
• Ultra-short bounce timesLong operating life.Unnecessary cut-in and cut-out of controlequipment is avoided.
Features • Standard versions with changeover switchPossible to obtain opposite switch functionor to connect a signal.
• Electrical connection at the front of the unitFacilitates rack mounting.Saves space.
• Suitable for alternating and direct current
• Cable entry of soft thermoplastics for cablesfrom 6 to 14 mm diameter.
P Polski Rejestr Statków, PolandDnV, Det norske Veritas, Norway
RINA, Registro Italiano Navale, ItalyBV, FranceLR, UKMRS, Maritime Register of Shipping, RussiaEZU, Czech Republic / Slovak RepublicCE according to EN 60730-2-1 to -9
Versions with UL and CSA approvals can besupplied to special order.
318 Catalogue RK.00.H5.02 Danfoss 9/96
Thermostats, type KP
KP 61
KP 62
KP 63
KP 68
KP 69
KP 62
KP 71
KP 73
KP 75
KP 77
KP 79
KP 81
KP 98 HT
KP 98 HT
−50 0 +50 +100 +150 +200°C
KP 98 OILKP 98 OIL
Vapour range
Adsorption charge
Ambient temperature−40 → +65°C (+80°C for max. 2 hours).
SwitchSingle pole changeover switch (SPDT).
Contact loadAlternating current:
AC1: 16 A, 400 VAC3: 16 A, 400 VAC15: 10 A, 400 VMax. starting current (L.R.): 112 A, 400 V
Direct current:DC13: 12 W, 220 V control current
Technical data Cable connectionCable entry for cables 6 → 14 mm dia.A Pg 13.5 screwed cable entry can be usedfor 6 → 14 mm dia. cables.With 8 → 16 mm cables a standard Pg 16screwed cable entry can be used.
EnclosureIP 33 to IEC 529This grade of enclosure is obtained when theunit is mounted on a flat surface or bracket.The bracket must be fixed so that all unusedholes are covered.IP 44 for single and dual versions with separatetop cover (accessories, must be orderedseparately, see KP pressure controls).
Regulating range
Contact systems
KP thermostats KP 98
Catalogue RK.00.H5.02 319 Danfoss 9/96
Thermostats, type KP
Ordering Charge Type Differential at Reset Code no.
1) Bulb must always be placed colder than the thermostat housing and capillary tube. The thermostat will then regulateindependent of ambient temperature.
2) Bulb can be placed warmer or colder than thermostat housing and capillary tube, but variations from +20°C ambienttemperature will influence the scale accuracy.
3) With manual switch, not isolating switch.4) Panel mounting model with top plate.5) Thermostats with gold-plated contacts.
Adsorb-tion 2)
Bulbtype
Setting range Max.bulb
temp.
Capillary-tube
length
320 Catalogue RK.00.H5.02 Danfoss 9/96
Ordering(continued)
Thermostats, type KP
Thermostat bulb types
A Straight capillary tube
B ∅ 9.5 × 70 mm remote air coil
C1: ∅ 40 × 25 mm air coilC C2: ∅ 25 × 67 mm air coil
(integral with thermostat)
D1: ∅ 10 × 85 mm double contact remote bulbD D2: ∅ 16 × 170 mm double contact remote bulb
Note! Cannot be used in sensor (bulb) pocket
F ∅ 25 × 125 mm remote duct coil
E1: ∅ 6.4 × 95 mm remote bulbE E2: ∅ 9.5 × 115 mm remote bulb
E3: ∅ 9.5 × 85 mm remote bulb
Catalogue RK.00.H5.02 321 Danfoss 9/96
Thermostats, type KP
DesignFunction
The switch in the KP has a snap-action functionand the bellows move only when the cutin or cut-out value is reached.
The design of the KP thermostat affords thefollowing advantages:− high contact load− ultra-short bounce time− vibration resistance up to 4 g
in the range 0-1000 Hz− long mechanical and electrical life.
1. Temperature setting spindle2. Differential setting spindle3. Main arm7. Main spring8. Differential spring9. Bellows
Dual thermostat KP 98 is used as a protectionagainst too high a discharge gas temperatureand to ensure a suitable oil temperature in thecompressor.To avoid the temperature of the hot gasexceeding the maximum permissible value duringextreme operating conditions (low evaporatingpressure, high condensing pressure, high suctionvapour superheat) a KP 98 thermostat can beused on the high temperature side (HT). If thetemperature of the hot gas becomes too high therefrigerant will break down and the compressordischarge valve will become damaged.The risk is greatest in refrigeration systems thatoperate on a high compression ratio (e.g. insystems with NH3 or R 22) and in applicationswith hot gas bypass.This unit has two separate thermostat functions.The HT sensor that controls the discharge gastemperature is fitted on the discharge tubeimmediately after the compressor.For larger compressors, the sensor can be builtinto the discharge tube.The OIL sensor that controls the oil temperatureis located in the compressor oil sump.
KP 98 is available in two versions:A. Protection against low oil temperatureCompressor manufactures recommend fitting aheating element in the crankcase to preventrefrigerant boiling out of the oil during start.
KP 98 is the correct thermostat for controlling thisheating element.
Why a heating element?During standstill, refrigerant is dissolved in thecrankcase oil. If the oil is cold and the standstillperiod long a large amount of refrigerant canbecome dissolved. This leads to two problems:1. When the compressor is started, the refrigerant
will boil off. There is a high risk of liquidhammer and consequent compressor damage.
2. The oil loses its lubricating capability when itis thinned with refrigerant.
To avoid these problems a heating elementcontrolled by a KP 98, 60L1132, should be fittedin the crankcase to keep the oil warm. This thenprevents dangerous amounts of refrigerant beingdissolved in the oil.
B. Protection against high oil temperatureCompressor manufactures recommend thatcompressors used in connection with industrialheat pumps or refrigerating systems be equippedwith a thermostat to give protection against toohigh an oil temperature in the crankcase.In periods of peak load, too high an oiltemperature leads to insufficient lubrication ofthe compressor, with the risk of compressordamage. KP 98, 60L1131, monitors the oiltemperature so that it cannot become too high.
DifferentialThe differential is the difference between themake and break temperatures.A differential is necessary for satisfactoryautomatic operation of the plant.
Mechanical differential (intrinsic differential)The mechanical differential is the differential setby the differential spindle.
Operating differential (thermal differential)The operating differential is the differentialthe plant operates on. Operating differential isthe sum of the mechanical differential and thedifferential produced by the time constant.
Reset1. Manual reset:
Units with manual reset can only be restartedafter the reset button has been activated.On min. reset units the set value is equal tothe cut-out value for falling temperature.On max. reset units the set value is equal tothe cut-out value for rising temperature.
2. Automatic reset:These units are automatically reset afteroperational stop.
Terminology
Catalogue RK.00.H5.02 323 Danfoss 9/96
Thermostats, type KP
Setting Thermostats with automatic resetSet the upper activating temperature on the rangescale.Set the differential on the "DIFF" scale.The temperature setting on the range scale willthen correspond to the temperature at which therefrigeration compressor will be started on risingtemperature. The compressor will be stoppedwhen the temperature has fallen in relation to thedifferential setting.Please note that the differential depends on therange setting. Therefore, the differential scalemust only be used as guideline.If with low stop temperature settings thecompressor will not stop, check whether thedifferential is set at too high a value!
Thermostats with minimum resetSet the stop temperature on the range scale.The differential is a fixed setting.The compressor can be restarted by pressingthe "Reset button" after the temperature on thethermostat sensor has risen by a value equal tothe fixed differential setting.
Thermostats with maximum resetSet the stop temperature on the range scale.The differential is a fixed setting.The compressor can be restarted by pressingthe "Reset button" after the temperature on thethermostat sensor has fallen to a value equal tothe fixed differential setting.
1. Vapour charge
Here the interdependence between the pressureand temperature of saturated vapour is utilized,i.e. the element is charged with saturated vapourplus a small amount of liquid.The charge is pressure-limited; a further increasein pressure after evaporation of all the liquid inthe sensor (17) will only result in a small pressureincrease in the element.
ChargesThis principle can be utilized in thermostats forlow temperature, etc. where evaporation must beable to take place from the free liquid surface inthe sensor (within the operating range of thethermostat), and where at the same time, thebellows must be protected against deformationwhen kept at normal ambient temperatures.Since the pressure in the element depends onthe temperature at the free liquid surface, thethermostat must always be placed so that thesensor is colder than the rest of the thermostaticelement.The evaporated liquid will recondense at thecoldest point, i.e. the sensor. Thus, as intended,the sensor becomes the temperature-controllingpart of the system.
Note: When the sensor is coldest, the ambienttemperature has no effect on regulating accuracy.
2. Adsorption chargeIn this case the charge consists partly of asuperheated gas and partly of a solid having alarge adsorption surface.The solid is concentrated in the sensor (17) andit is therefore always the sensor that is thetemperature-controlling part of the thermostaticelement.The sensor can be placed warmer or colderthan thermostat housing and capillary tube, butvariations from +20°C ambient temperature willinfluence the scale accuracy.9. Bellows element
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