Brochure/Catalogue

for EMR for SSR
Insulating material group According to their CTI (comparative tracking index) values, the insulating
materials are categorised in one of the following four groups:
Group I 600 CTI
Group II 400 CTI < 600
Group IIIa 175 CTI < 400
Group IIIb 100 CTI < 175
The gures for the comparative tracking index, according to IEC 60112
(DIN IEC 60112 / DIN VDE 0303-1) are determined using special samples
prepared for this purpose with test solution A.
x x
L
Leakage current The current on the load side of a solid-state relay that ows when the output
stage is in the locked state. It ows because a solid-state relay does not provide
galvanic isolation of the output, as is the case when there is an air gap when the
contact of an electromechanical relay is open. The output of a solid-state relay
only becomes high-impedance when it is locked, meaning that only a very small
amount of current is owing. Solid-state relays with AC output often have an
RC protective suppressor circuit in parallel to the output, which is why leakage
currents of up to 2 mA can ow in the locked state.
x
Load limit integral (I²t) The load limit integral (I²t), specied in A²s, is the pulse-shaped (< 10ms) short-
term overload capacity of the semiconductor switch in solid-state relays or
semiconductor contactors.
It is used to select a fuse as device protection for the output of a semiconductor
switch.
If this value is exceeded, the semiconductor switch may be destroyed; when
selecting the fuse size, it is therefore recommended that the I²t of the fuse is half
the size of the semiconductor switch.
x
M
Max. reset time in the case
of a voltage interruption,
recovery time
Time that needs to elapse after the excitation variable has been switched off in
order for the timing relay to full a function again as specied.
x x
Max. switching frequency
(DC and AC control voltage)
Number of switching cycles per time unit of a solid-state relay with continuous
current and resistive load.
When switching inductive loads with switching frequencies faster than 0.5 Hz,
an external protective suppressor circuit must be connected in parallel with the
load.
If this is not possible, solid-state relays specially designed for switching inductive
loads must be selected.
Due to the input wiring of the solid-state relay (e.g. bridge rectier and smoothing
capacitor), different switching frequencies can often be implemented for solid-
state relays with AC/DC (UC) input. These specications are therefore listed
separately in the data sheet.
x
Max. switching frequency
at rated load
Number of switching cycles per time unit of an electromechanical relay at max.
switching capacity and resistive load.
The switching frequency for small and medium loads can be higher than the
value specied in the data sheet if the switching characteristics of the load (such
as arcing) do not overload the contact to an inpermissible extent.
x
EMR = Electromechanical relay
SSR = Solid-state relay
Glossary: Relay modules and Solid-state relays
W
Technical appendix/Glossary
W.26 2737920000