Danfoss KPU 1, KPU 2, KPU 5, KPU 15, KPU 6 Data sheet

Data Sheet

Pressure switch
Type KPU

The KPU pressure switches are designed for use
in refrigeration and air-conditioning systems to
protect the systems from excessively low
suction pressure or too high discharge
pressure. They can also be applied to start and
stop compressors and the fans of air-cooled
condensers.

The KPU pressure switches, in single and dual
versions cover a comprehensive range of
applications, and are designed for use with
HCFC and non-ammable HFC refrigerants.

Features:

• Snap action electrical contacts minimize
chatter, bounce, and wear, and ensure
longterm electrical and mechanical reliability

• The fail-safe dual bellows used in KPU 6 and
KPU 16 prevent refrigerant loss and enable
premature cut-out when a fault occurs

• SPDT or SPST switch a in single control
models. SPST or SPDT with high-low pressure
signal in dual control models

• Manual trip function (electrical contact
function can be tested without the use
of tools)

• Easily replaces Johnson Controls and Ranco
products

• Wide pressure range:from low pressure KPU 2
with narrow dierential to KPU 6 and KPU 16
for high pressure refrigerants (R410A, R744)

• Automatic, manual or convertible reset
versions available

• Vibration and shock resistant

AI216886432210en-000901

Unit type

Material

KPU 1, KPU 2, KPU 5, KPU 15

Tin bronze, no. CW452K, EN 1652 Nickel plated free cutting steel, no. 1.0737/ 1.0718 to EN 10277

KPU 6, KPU 16

Stainless steel bellows

KPU with capillary tube

Copper SF-CU no. 2.0090 to DIN 1787

Ambient temperature

-40 – 122 °F (175 °F for max 2 hours)

Maximum working pressure

Low pressure (LP)

KPU 1, KPU 2 and LP side of KPU 15, KPU 16: 250 psig

High pressure (HP)

KPU 5 and KPU 15 on HP side: 510 psig

KPU 6 and KPU 16 on HP side: 675 psig

KPU 6 and KPU 16 on HP side: 610 psig for products used according to 2014/68/EU PED direc­tive

Maximum testing pressure

Low pressure (LP)

KPU 1, KPU 2 and LP side of KPU15, KPU16: 290 psig

High pressure (HP)
KPU 5 and KPU 15 on HP side: 530 psig

KPU 6 and 16 on HP side: 725 psig

Cable entry

7

⁄8 in cable entry for 1⁄2 in male pipe thread connection (conduit boss)

Contact load
Alternating current

FLA = 24 A @ 120 V AC

24 A @ 240 V AC

LRA = 144 A @ 120 V AC

144 A @ 240 V AC

LRA is rated for make only

Direct current

240 V DC: 12W pilot duty

Wire dimension

10 AWG maximum

Enclosure

~NEMA 1

Pressure switch, KPU

Product specication

Materials in contact with medium

Table 1: Materials

Technical data

Table 2: Technical data

Terminology

Set point

A predetermined value to which a switch is adjusted and at which it performs its intended function.

Reset

1. Manual reset
A unit with manual reset can only be restored to operational mode by activating the external reset button.

2. Automatic reset
A unit with automatic reset is restored to operational mode automatically.

3.Convertible reset
A unit with convertible reset can be adjusted for either automatic or manual reset.

Maximum working pressure

The maximum permissible pressure for safe functioning of a refrigeration system or any of its parts.

Maximum test pressure

The maximum pressure applied in strength or leakage tests on refrigeration systems or components thereof.

Dierential

Dierential is the number of psi (or bar) by which cut-in and cut-out set points are separated.

Snap function

A specic contact force is maintained until snap is initiated. The time over which contact force reaches zero is a few
milliseconds; therefore, contact bounce cannot occur as a result, for example, of slight vibrations before cut-out. The
snap-action contact system will continue to function even when micro-welds are created between the contacts
during cut-in. The force created to separate the contacts is strong, and instantly shears o all contact surface welds
that have been created as the result of cut-in action. These design features ensure that the cut-out point of the KPU
switch remains very accurate and completely independent of the magnitude of the current load.

© Danfoss | Climate Solutions | 2021.02 AI216886432210en-000901 | 2

Pressure switch, KPU

Fail-safe switch

A switch is fail-safe if it has the capability to remain in a safe condition or transition to a safe condition when a fault
occurs.

FLA – Motor Full Load Amperes

The current rating, in amperes, of the motor when a full load is applied to it for work being done.

LRA – Locked Rotor Amperes

The current drawn, in amperes, by an electric motor with the shaft or rotor stopped and locked in position.

Setting

Cut-in and cut-out pressures for both LP and HP sides of the system should always be checked with an
accurate pressure gauge.

Low Pressure setting for switches with automatic reset

1.

Set the LP cut-in pressure on the “CUT-IN” scale (range scale). One rotation of the low pressure spindle ~ 5.2 psi
for KPU 2 and ~6.8 psi for KPU 1.

2.

Set the LP dierential on the “DIFF” scale. One rotation of the dierential spindle ~ 3.2 psi for KPU 2 and 2.9 psi
for KPU 1.

NOTE:



The LP cut-out pressure is LP cut-in pressure minus dierential value. The LP cut-out pressure must be above
absolute vacuum (Pe = 29.5 in Hg).

High Pressure setting for switches with automatic reset

1.

Set the HP cut-out pressure on the “CUT-OUT” scale. One rotation of the HP spindle ~ 22 psi for KPU 5 and ~ 28
psi for KPU 6.

2.

Set the HP dierential on the “DIFF” scale. One rotation of the dierential spindle ~ 5.3 psi for KPU 5 and ~ 8.6 psi
for KPU 6.



NOTE:

The HP restart pressure is equal to HP cut-out pressure minus dierential.

Pressure switches with manual reset Set the cut-out pressure on the “CUT-OUT” scale (range scale). Low Pressure
switches can be manually reset when the pressure is above the cut-out pressure plus the dierential. High Pressure
switches can be manually reset when the pressure is below cut-out minus dierential.

© Danfoss | Climate Solutions | 2021.02 AI216886432210en-000901 | 3