2Specifications are subject to change without notice
Sockets◊S 411
Hold down spring◊HF
Mounting rack SM 13
Socket covers BB 4
Front mounting bezel FRS 2
Potentiometer lock PL 2
For further information refer to "Accessories".
AccessoriesTime/Range Setting
Range setting
Upper potentiometer:
Adjustment of upper limit in
percent.
Middle potentiometer:
Adjustment of lower limit in
percent.
Hysteresis
1-3% of rms-value
Time setting
Bottom potentiometer:
Time setting on relative scale
(not SYY 155).
Time
Adjustable delay on release:
0.2 to 10 s
S 1721, SYY 155
Reaction time τ= 2 s, worst case reaction
time may be up to 5 x τ
Adjustable delay on release
built-in (0.2s - 10s)
Note:
Reaction time + set time =
real delay on release time
Accuracy
OFF delay 10s, -1/+3 s on max.
< 0.1 s on min.
Time function
Delay on release 0.2-10 s. adj.
Indication for
Power supply ON LED, green
Output ON LED, red
Environment (IEC 60947-1)
Degree of protection IP 20 B (IEC 60529)
Pollution degree (IEC 60664)
1: S 1721 380/400/415
SYY 155 380/415
2: S 1721 220, SYY 155 220
Operating temperature -20° to +50°C (-4° to +122°F)
Storage temperature -50° to +85°C (-58° to +185°F)
Weight 200 g
Approvals UL, CSA
Power supply AC types Overvoltage cat. III (IEC 60664)
Rated operational voltage (IEC 60038)
Through pins 5, 6, 7 & 11 220 3 x 220 VAC ± 18%,
(neutral) 45 to 65 Hz
380 3 x 380 VAC ± 18%,
45 to 65 Hz
400 3 x 400 VAC ± 18%,
45 to 65 Hz
415 3 x 415 VAC ± 18%,
45 to 65 Hz
Voltage interruption ≤40 ms
Dielectric voltage None (supply/elect.)
Rated impulse withstand volt. 4 kV (1.2/50 µs) (line/neutral,
line/line), direct connection
to electronics
Internal measuring circuit is
connected to pins 5 & 11
Rated operational power 3.5 VA
Mode of Operation
Connected to 3 phases and
neutral, the S 1721 and SYY
155 measure sinusoidal vol-
tages. The phase sequence is
arbitrary.
The relay operates as long as
all 3 phase-neutral voltages
are within the set upper and a
lower limit. The two limits are
set separately.
For S 1721 applies that if one
or more of the phase-neutral
voltages rises above the up-
per limit or drops below the
lower limit, the relay releases
after the set time period
whereas SYY 155 releases
immediately.
The relay operates again
when all 3 phase-neutral vol-
tages are within set limits.
Hysteresis on operate is 2%.
Example 1
Mains monitoring
The relay measures if the 3
phase-neutral voltages are
within the upper and lower
limits. The limits are adjusted
on the two built-in potentio-
meters.
Example 2
Monitoring load supply
The relay can protect loads,
such as heating elements,
against overvoltage and
thereby against increase in
current, which could otherwise
destroy the heating elements.
Undervoltage to ohmic loads
causes insufficient heating
capacity, and this can also be
monitored.
The relay cannot be used for
load monitoring if the load is a
motor, as the regenerated
phase voltage at e.g. fuse
blowing is indefinable and
dependent on the mechani-
cal performance when the
failure occurs.
Supply Specifications General Specifications