Current and Voltage Controls
3 Phase-neutral Max. and Min. Voltage Control
Types S 1721, SYY 155
• Monitoring relay for 3-phase upper/lower
phase-phase neutral voltage control
• Measures if all 3 phase-neutral voltages are
within set limits
• Measures on own power supply
• Operates irrespective of phase sequence
• Upper and lower limits separately adjustable
• Built-in adjustable timer function
• Output: 10 A SPDT relay
• Plug-in type module
• S-housing
• LED-indication for power supply and output ON
• Power supply is the 3-phase + N measuring voltage
Product Description
Ordering Key
S 1721 156 220
3-phase and neutral moni- is unstable or varies in value Housing
toring plug-in relay for sepa- in order to monitor that the Type
rate upper and lower voltage attached motors are perfor- Output
control. Often used to control ming as required. The S 1721 Power supply
all 3 phases and neutral where features built-in time delay.
the supplied electrical power
Type Selection
Plug
Output
Timer
Supply: 220 VAC
S 1721 156 220
Supply: 380 VAC
S 1721 156 380
Supply: 400 VAC
S 1721 156 400
Supply: 415 VAC
S 1721 156 415
Circular SPDT
Circular SPDT
Yes
No
SYY 155 220
SYY 155 380
SYY 155 415
Input Specifications
Output Specifications
Input
Pins 5, 6 & 7
Pin 11
Output
Rated insulation voltage
SPDT relay
250 VAC (rms)
(cont./elect.)
Arbitrary phase sequence
Neutral
Measuring ranges (VAC)
Contact ratings (AgCdO)
µ (micro gap)
Power supply (phase-phase) 3x220 +N 3x380 +N 3x400+N
Resistive loads
AC 1
10 A/250 VAC (2500 VA)
1 A/250 VDC (250 W)
10 A/25 VDC (250 W)
2.5 A/230 VAC
5 A/24 VDC
≥ 30 x 106 operations
± 18% ± 18% ± 18%
DC 1
or
Range (phase-neutral)
Upper level
Scale
Lower level
Scale
104-150 180-260 188-271
130-150 225-260 235-271
102-118% 102-118% 102-118%
104-124 180-215 188-225
82-98% 82-98% 82-98%
Small inductive loads AC 15
DC 13
Mechanical life
Electrical life
AC 1
≥ 2.5 x 105 operations
(at max. load)
Power supply (phase-phase)
3x415+N
Operating frequency
Dielectric strength
Dielectric voltage
Rated impulse withstand volt. 4 kV (1.2/50 µs) (cont./elect.)
(IEC 60664)
≤ 7200 operations/h
± 18%
Range (phase-neutral)
Upper level
Scale
Lower level
Scale
204-276
252-276
102-118%
204-228
82-98%
≥ 2 kVAC (rms) (cont./elect.)
measures value of own
supply. Range equals rms
value of a sinusoidal voltage
Specifications are subject to change without notice (26.10.99)
1