Digital protection set dedicated to low power generator-transformer or generator unit
CZAZ-GTM (CZAZ-G) is a protection set providing complex protection of generator-transformer unit of low generation power against every type of fault or improper working conditions. CZAZ-GTM/G protection is designed in digital technology, it provides both general and specialised protection functions, it generates trip signals and alarms, as well as it measures custom electrical values, it records analog and binary signals and it communicates with control system. Protection functions are chosen from protection function library and they depend on a number of analog inputs and capabilities of digital filtering module.

Manuals, diagrams, technical details


Product description

Protection set

Protection functions available in CZAZ-GTM(G) are listed below:

87G Differential of generator
87T/B Transformer/Power unit differential
51G Overload/overcurrent protection of generator stator
21 Impedance-based of power unit
32 Reverse power protection
59 Overvoltage
27 Undervoltage
40/27 Against loss of excitation of generator
81 Over-/underfrequency
24 Transformer overexcitation volt per hertz protection
46 Negative sequence, definite-time overcurrent protection
46inv Negative sequence, inverse-time overcurrent protection
59GN Generator residual overvoltage protection
64R Earth fault protection of generator rotor

Protection functions are supported by logic circuits, which are designed using available measuring functions, Boolean operators and timers. It allows to configure advanced automation circuits, for example:


  • breaker failure logic, which provides redundancy trip signal of electrical part of power unit in case of failure operation of generator breaker
  • control generator excitation system, used in case of occurance of disturbances requring immidiate generator excitation system switch off
  • Against connection of unexcitated generator (50/27)

Main features

  • Up to 19 analog inputs. The type of analog inputs adjusted to the set of instrument transformers applied in particular protected object
  • 16 binary inputs for external protection relays
  • 4 relay outputs for triping purpose (3 outputs allows to direct connection with breaker coils)
  • 12 relay outputs for signalling purpose
  • Possibility to adapt easily protection functions characteristics with biult-in software, disigning logical circuits, timers and control algorithms, registers and signalling. The configuration of protection unit is carried out by the manufacturer or authorised representative
  • Possibility to group signals in any configuration in order to get logical sum of trip signals
  • Measuring of electrical values (current, voltage, active and reactive power, frequency, phase shift, resistance, reactance, apparent impedance)
  • Event recorder (256 unique events, capacity up to 5000 events, time resolution 1 ms)
  • Disturbance recorder:
    • sampling frequency 1800 Hz
    • recording up to 40 analog signals and up to 128 binary signals
    • duration of recorder waveform – up to 500 sec. for one signal (approx. 10 sec. for 40 analog signals and 128 binary signals)
    • memory allows to safe up to 32 files of registered disturbances
    • recording of sampled or digital filtered values (e.g. differential currents)
  • Optical signalling at HMI (14 LED diodes)
    • auxilliary voltage signalling
    • proper work of unit signalling
    • 12 programmable diodes for signalling other statuses
  • Expanded self-control system and failure signalling
  • Autonomic communication by local HMI
  • Remote communication with PC computer or SCADA system (two RS485 ports and one RS232 in front panel)
  • Free PC software for Windows operating system
  • Enclosure addepted for surface mount


Rated current In 1A or 5A
Rated voltage Un 100V
Rated frequency fn 50Hz
Rated auxilliary voltage Up 110V or 220V DC
Burden in current inputs ≤1VA/input
Burden in voltage inputs ≤0,2VA/input
Continous thermal withstand of current inputs 2,2In
Continous thermal withstand of voltage inputs 2Un
1 sec thermal withstand of current inputs 50In
Dynamic withstand of current inputs (10 ms) 125In
Relay outputs data:
Control purposes outputs:
Breaking capacity (DC or AC 50Hz) 5A
Continuous contact carry 5A
Signalling purposes outputs:
– resistive load (220V DC) 0,3A
– inductice load (220V DC, L/R=40 ms) 0,12A
Continuous contact carry 3A
Ambient temperature (268÷313)K/(-5÷40)°C
Relative himidity ≤80%
Ingress Protection degree IP40
Weight ≤35 kg
Dimensions (height x width x depth) 529 x 370 x 275 mm
Electromagnetic compatibility according PN-EN 50263
Insulation according to PN-EN 60255-5

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