Brochure

ESG
8.658.65
8.658.65
8.65
Ambient temperature range. The surrounding air
temperature limits, usually given for both operating and
storage conditions. The maximum operating tempera-
ture may require close consideration by the thermal
dictates of heat dissipation and the possible requirement
of a heat sink.
Anode - Connection of a thyrisor. High potential
terminal on an SCR. Positive in respect to gate and
cathode when conducting (blocking when negative).
Base. The control terminal of a bipolar transistor.
Bipolar. Generally used to describe a transistor type in
which a dc current flow between collector and emitter is
modulated by a smaller current flowing between base
and emitter. The gain of the transistor relates to the ratio
of these two current defined as beta or hfe in common-
emitter configurations.
Bistable. A two state device that will remain in its last
operated state after control power power is removed
(e.g. latching relay).
Blocking voltage. Maximum allowable standoff
voltage before breakdown.
Breakdown (Breakover). The point at which blocking
capability in an SSR colapses as voltage is increased
beyond its maximum (transient) rating.
Capacity. The ability to store an electrical charge. Also
given as an SSR isolation parameter, measured input to
output, or both to case, provided as a means of determi-
ning high frequency noise coupling.
Cathode. SCR terminal associated with gate terminal.
Negative in respect to anode when conducting.
Collector. A main current terminal and also high
voltage terminal of a transistor relative to the base and
emitter.
Control voltage. Specified as a range of voltages
which, when applied across the SSR input terminals, will
maintain an on condition accross the output terminals.
di/dt. Maximum rate of rise of on state load current that
an SSR can withstand without damage. A characteristic
of thyristors used in ac SSRs.
du/dt (rate of rise of voltage) in blocking state
(static). Maximum rate of rise of voltage applied across
the output terminals that the SSR can withstand without
turning on. A characteristic of thyristors used in ac SSRs.
Emitter. A main current terminal of a transistor, also
associated with the base terminal and its control current.
FET. Field Effect Transistor. Principle of operation
differs from that of bipolar types. Voltage applied
between gate and source terminals modulates the
device resistance to current flow between drain and
source terminals, by means of a field set up in the
channel region.
Holding current. The minimum (load) current requi-
red to maintain a thyristor in its conducting state.
I
2
t (Maximum). Nonrepetitive pulse current capability
of SSR given for fuse selection. Expressed as "ampere
squared seconds" with typical half cycle pulse width.
Inductance. An electrical property which can oppose a
current change and also store a charge. The unit of
inductance is called the Henry [H].
Input current (Maximum). Current drain on the
control source at specified SSR input voltages and on-
off conditions.
Input Impedance/Resistance. Minimum effective
SSR input resistance at a given voltage which defines
input power and sensitivity.
Instantaneous turning on. After applied control
power the SSR switches to on independently of the
momentary phase-angle.
Insulation Resistance (Minimum). Resistive value
usually measured at 500 volts dc, input to output, or
both to case.
Leakage current. The current conducted through the
SSR output terminals, in the off state.
Load Current (Maximum). The maximum steady-
state load current capability of an SSR, which may be
further restricted by the thermal dictates of heat sink and
ambient temperature conditions.
Load Current (Minimum). The minimum load
current required by the SSR to perform as specified.
Load voltage (Maximum). The range of minimum to
maximum mains voltage, that can be applied to the
outputs of the SSR.
Maximum capacity input to output. Maximum
value of capacitive coupling between control terminals
and power output terminals.
Maximum overcurrent (not repetitive). Maxi-
mum allowable SSR momentary current flow for a
specific time duration. (Typically expressed as an RMS
value for a one second duration).
MOSFET. Metal Oxyde Semiconductor Field-Effect
Transistor. The control electrode (gate ) is generally
isolated from the source electrode by a layer of silicon
oxide. A voltage applied between the gate and the
source will provide a current flow between drain and
source.
MOV. Metal Oxide Varistor, commonly used with ac
SSRs to suppress bidirectional voltage-dependent
resistive characteristic that drop rapidly with increasing
voltage.
MTBF. Mean Time between failure.
On State Voltage (Maximum). The peak voltage
that appears across the SSR output terminals at full
rated load.
Glossary of terms