SYNCHROTACT® 5 Operating Instructions SYN 5201 SYN 5202

Functional principle 

2.1 Brief description 

The SYNCHROTACT 5 digital synchronizer is used for automatic synchronizing and 

paralleling of generators with lines and for the paralleling of already synchronous lines. 

The device is designed for system frequencies of either 50/60 Hz or 16 2

/3 Hz. 

SYN 5201 is a single-channel synchronizing device whose component choice and 

software design provides the highest security against incorrect paralleling. 

SYN 5202 consists of two independent channels with different hardware and software. 

This dual-channel property maximizes security against incorrect paralleling. 

All parameters required for paralleling are stored in a parameter set. The paralleling 

conditions and the characteristics of the voltage and frequency matchers are defined in 

this set. With the option providing seven parameter sets, paralleling can be carried out 

under different conditions or with different matcher characteristics using the same 

device. Seven configurable digital inputs and outputs are available for the selection and 

back indication of a parameter set. 

The data which are important for commissioning and for control purposes can be 

uploaded or downloaded using the PC tool SynView or, alternatively, via the keypad on 

Paralleling functions 

The automatic paralleling process can basically be divided into four function blocks: 

1. Measuring 

2. Voltage and frequency matching 

3. Monitoring of paralleling conditions 

4. Paralleling command generation 

In the following figure, the block circuit diagram of the basic paralleling functions of 

SYNCHROTACT 5 is simplified and shows a single-channel configuration. The 

individual functions are described more precisely in the following sections. 

Measuring 

The following measured variables are generated from the two single-phase measuring 

voltages: 

Voltage U1, U2 

U1 is the reference voltage e.g. line 

U2 is the adjustable voltage e.g. generator. 

Frequency f1, f2 

f1 is the reference frequency 

f2 is the adjustable frequency. 

Voltage difference ΔU 

ΔU = IU1I – IU2I 

ΔU > 0 Adjustable voltage is lower 

ΔU < 0 Adjustable voltage is higher 

Slip s 

%100*

1

21

f

ff s − =

s > 0 Adjustable frequency is less (e.g. generator is sub-synchronous) 

s < 0 Adjustable frequency is greater (e.g. generator is oversynchronous) 

Phase-angle difference α

α ϕ −= ϕ21

α > 0 Adjustable frequency is lagging 

α < 0 Adjustable frequency is leading 

Acceleration ds/dt 

dtds [ ]ss

x

x

x /%*2/

56

1

∑

=

=

Δ=

(Every 0.5 s, an average value is formed from 56 measurements; sampling period: 

9 ms) 

ds/dt > 0 Adjustable frequency is reduced (e.g. generator accelerates) 

ds/dt < 0 Adjustable frequency increases (e.g. generator is slowed down) 

With SYN 5202, the measurement is carried out separately for each channel. It is 

possible to carry out three-phase measurements in order to detect connection faults 

(rotary field, polarity) and losses of phase.

Voltage measurement (SYN 5202: channel 1) 

The two input voltages U1 and U2 are passed to the processor via high-impedance input 

resistors, differential amplifiers, low-pass filters and A/D converters. 

Voltage measurement channel 2 (SYN 5202 only) 

The two input voltages U1 and U2 are passed through high-impedance input resistors 

and differential amplifiers. The signal for the amplitude value is formed from this by 

conversion and filtering . For zero-passage detection, the signal is filtered and passed 

through a comparator. The signals prepared in this way are passed to the processor via 

the A/D converter

Voltage and frequency matching 

Working range of the voltage matcher 

If the voltage U1 is in the range between Umin and Umax and the voltage U2 is greater 

than U0max the adjusting commands are released. The direction of the adjusting 

commands depends on the polarity of ΔU. 

As an additional condition, both frequencies must be in the range fn±5 Hz. 

Voltage matcher with variable pulse times 

The voltage matcher issues a command the length of which is proportional to the current 

voltage difference. The proportionality factor dU/dt can be adapted to the voltage 

regulator. The voltage matcher aims at a value in the middle of the set tolerance band. 

The adjusting command length tp U is: 

dtdU

U U

U

tpU /

2

max max

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ Δ−−Δ+

−Δ

=

The adjusting pulse is discontinued as soon as the voltage difference passes through 

the target value. The command length does not fall below a settable minimum value. 

After an adjusting command, the system waits for the set pulse interval ts U so that the 

actual values can stabilise to the new setpoint. 

Voltage matching with variable intervals 

The function INVERSE U changes the way the voltage matcher functions. The pulses 

are now always the same length, but the intervals are inversely proportional to the