C
22 Posts in this encyclopedia categoryCard relay (plug-in/print relay)
Card relays, also called plug-in/print relays, are used for galvanic
isolation of circuits as well as for signal matching and signal
amplification. The horizontal and vertical versions allow optimal
adaptation to their application.
Category (C)
Classification of the safety-related parts of a control system with
regard to their resistance (K, B, 1, 2, 3, and 4) to faults and their
behaviour in the event of a fault, which is achieved on the basis of the
structural arrangement of the parts and/or their reliability. [DIN EN
954-1, see also DIN EN ISO 13849-1]
Cleaning / Washing
In accordance with the protection class for wash-tight relays, RT
III, the relays can be washed in a suitable cleaning medium. For
environmental reasons, we recommend not cleaning the assemblies. Should
cleaning be necessary for certain reasons, the following procedural
criteria must be observed:Cool down the assembly as previously described.The temperature of the washing medium should not exceed 55 °C and the washing time should be as short as possible (e.g. 2 min).Do not use ultrasonic cleaning to avoid possible contact adhesion.Do not use cleaning additives. If a detergent is used, make sure that it does not damage the relay or the seal.Avoid high-pressure cleaning
Clock generator
Function as with the flasher relay, except that the pulse time and pause
time are different and can therefore be set separately.
Closed-circuit current principle
With the closed-circuit current principle, the contact falls back
into the rest position as soon as the response condition is fulfilled.
Coating, painting or potting
For some applications, printed circuit boards must be painted or
encapsulated. Only relays with protection class RT III should be used
for this purpose. We recommend one-component lacquers based on epoxy or
polyurethane resins applied by spraying. Silicones or materials
containing silicone must not be used. Special suitability tests of the
paint must be carried out. Due to capillary action, the lacquers can
creep between the relay and the PCB. During the subsequent drying or
curing process, they may not cure completely there. Lacquer vapours may
then penetrate into the interior of the relay and impair its
functionality. If the PCB is encapsulated with the relays, heat
dissipation may be altered by the encapsulation. The user must carry out
additional tests to check whether the performance data of the relays
may have to be reduced.
Command device
The command device expands the key transfer system with variable
command, signalling, dialling and emergency stop functions. The system
thus becomes a "control centre" from which, among other things, command
functions can be controlled. The module can be installed with the key
transfer system and thus enables direct command execution at access
points of machines and systems.
Common cause of failure (CCF)
Failures of different units due to a single event, whereby the failures are not based on mutualcause.
Consent switch
The enabling switch must be operated manually so that the protective
effect of the guards can be cancelled. It alone must not be used to
initiate hazardous conditions. A "second, conscious" command is required
for this.
Contact lifetime
Electrical service life indicating the expected number of switching cycles at a defined load, e.g. AC 15.
Continuous current
This is the current that a relay contact may carry continuously without
exceeding the permissible temperature rise in relation to the defined
ambient conditions.
Control cabinet housing
Modern electronics require innovative enclosure solutions. The
enclosures are available in all common widths from 6.2 to 200 mm with a
choice of screw or spring-loaded terminals for installation in control
cabinets.The enclosure system, which is available in many
colours, offers a wide range of applications and designs. In addition,
it is characterised by an unmistakable design and maximum functionality.
The universal enclosure system includes all standard widths available
on the market, from the 6.2 mm narrow compact solution to the 90 mm wide
large-capacity enclosure. Special widths are also possible. The
connection technology is extremely variable and freely selectable. This
means that the signal density or the number of poles can be conveniently
varied according to requirements. On three terminal levels, up to 30
connections are possible with a width of 22.5 mm.The modular
enclosures are also available with a sealable, transparent front cover.
This reliably protects memory cards, sockets and setting elements from
manipulation and accidental misadjustment.
Control category (CC)
Classification of the safety-related parts of a control system with
regard to their resistance (SK B, 1, 2, 3, and 4) to faults and their
behaviour in the event of a fault, which is achieved on the basis of the
structural arrangement of the parts and/or their reliability [EN
954-1].
Cooling of wash-tight relays
After wave soldering, the assembly must be cooled down as gently and
stress-free as possible to the desired low and constant temperature in a
cold air flow before the washing process. If a washing process follows,
this temperature must be matched as closely as possible to the
temperature level of the washing medium. The optimum cooling gradient
for this must be determined individually for the relay or the assembly
under original process conditions. The recommended cooling gradient is
in the range of 0.5 K / s to 2.5 K / s. As part of the qualification of
the assembly, the optimum cooling process must be determined and used as
a basis for processing. This avoids possible damage, such as
micro-cracks on the relays (and also other, neighbouring components).
Too rapid cooling or sudden temperature changes, which could have an
effect on the assembly as a cold shock, must not take place.
Coupling modules
Coupling modules are designed with positively driven contacts according
to IEC 61810-3. The positively driven NC contacts enable monitoring of
the NO contacts. As links between logic and load, they serve to switch
safety-related functions
Coupling relay
Electronic controls have long been an integral part of modern
automation technology. As early as the beginning of the 1970s, they
gradually replaced the contactor and relay controls that had been common
until then. This reduced the power consumption of the controls, which
work with extra-low voltages, to a minimum. However, the energy
requirements of the power level for driving motors, magnetic couplings
or hydraulic cylinders have not changed until today. They still require a
correspondingly high amount of electrical energy.Coupling relays
therefore take over the necessary adaptation of logic and power level.
They also ensure safe isolation. This makes coupling relays the ideal
links between the highly sensitive, almost powerless logic level of a
PLC, control system or process computer and the rough operation on the
machine.
Creepage distance
Is the shortest distance along the surface of an insulating material between two conductive parts.
Cross-circuit detection
Ability of a SAG to cross-connect immediately or within the scope of
cyclical monitoring, after detection of the fault, to assume the agreed
safe state.
Cross-connection
Electrically conductive connection / short circuit between the input
channels of an emergency stop module. A cross-circuit can only occur
with multi-channel unit control.
Current monitoring
To ensure blocking protection, the motor current in T3 is monitored.
The switching threshold is adjustable via potentiometer. This provides
permanent protection of the motor and machine against overload.
Current relay
Current relays monitor AC and DC currents for exceeding or falling
below a set threshold. Depending on the current relay, one or more
consumers can be checked with one device. Current relays are used, among
other things, in stone and woodworking machines and wherever it is
necessary to monitor voltages.
Cyclic test
Before or at the next request of the safety function, an error is
automatically detected, i.e. at the latest at each switch-on cycle of
the evaluation unit.