MS220KA and MSR220KA
10580-0701-04-GB
Page
4 / 12
www.ziehl.de
4
Application and brief description
Ziehl PTC thermistor relays protect motors, transformers, machines and equipment against thermal
overload. Used in conjunction with respective PTC thermistors they provide a reliable temperature protection
in the temperature range 60 °C up to 180 °C.
ZIEHL PTC thermistor relays are conform to EN 60947-8 and are thus exchangeable. PTC-thermistors
according DIN VDE V 0898-1-401 (replacement for DIN 44081 and DIN 44082) shall be connected. PTC
thermistors are suitable for the installation into windings of electrical machines, bearings and transformers
as well as to monitor the temperature of liquid media, airflow and gases. With ATEX approval, explosion-
protected equipment in explosive gas atmospheres (marking G: gas) or in areas with combustible dust
(marking D: dust) can be protected.
5
Summary of functions
•
1 thermistor circuit for 1…6 PTC thermistors
•
Short-circuit detection within the thermistor circuit
•
Output relay with 1 or 2 change-over contact (co)
•
Operating status display with LED
A current monitors continuously the resistance of the sensors. In cold state, the resistance is <250 Ω per
sensor (sensor circuit < 1.
5 kΩ). The relay has picked up and contacts 11/14 (21/24) are closed. The
resistance of the thermistor rises rapidly at detector operating temperature TNF. The relay release at a
resistance of
3…4 kΩ and contacts 11/12 (21/22) close. The devices also switch off in the case of detector
or line short-
circuit (< approx. 20Ω) or detector or line interruption. MS types switch on automatically when
the temperature has decreased approx. 5 °C. MSR types store the switch-off and must be reset (to be
acknowledged) manually with the built-in key button or an external push-button. Power-on is recognized as
an automatic reset. With bridged terminals Y1 and Y2, the function reclosing-lock is disabled. Then the
device works like type MS.
6
Connecting diagram
Us = supply voltage
S1 = off-switch
S2 = push-button on
S3 = remote reset
H1 = indicator lamp fault
F1-F4 = fuses
K1 = contactor
1) = only with 2 co
2) = only MSR