Gefran GTT 25A, GTT 40A, GTT 50A, GTT 60A, GTT 75A Data Sheet

GTT 25 / 40 / 50 / 60 / 75 / 90 / 120A

POWER SOLID STATE RELAYS WITH ANALOG CONTROL

Main applications

• Plastics extrusion lines
and injection moulding
machines

• Polymerization plant for
synthetic fibre production

• Rubber moulding
machinery

• Driers for ceramics and
components for the
building industries

• Chemical and
pharmaceutical industries

• Industrial electric ovens

• Food processing plants

PROFILE

The GTT family of solid-state relays
has been designed with the aim of
providing very accurate control of the
load thanks to an analog control input, in
voltage at 0…5V; 0…10V or in current at
0…20/4…20mA or a potentiometer (from

1KΩ to 10 KΩ).

The electronic design ensures that the
cycle time for proportioning the power is

automatically optimized.

The number of cycles that the GTT

supplies to the load (wave trains) for

a given input signal is calculated to be
the minimum possible to maintain the

necessary accuracy.

This guarantees a very fast and accurate
control loop that enables the GTT, driven
by a controller or a PLC with analogue

output, to obtain very precise control.

The GTT can be used in three phase
systems, using master-slave control
architecture in which the control signal

drives only one GTT (master) and this

unit supplies the synchronized signals to

the other GTT slaves.

Two GTS modules can also be used as

slaves.

A load interrupt control option (HB)

is available without having to use an
external current transformer; alarm limit
is settable with trimmer and yellow LED
signal, with voltage-free contact, normally

open.

The GTT solid-state relay has a green
LED to indicate the presence of the
24Vac power supply and a red LED
to indicate the switching based on the

analog control input signal.

The LED signal will be continuous (off at

minimum, on at maximum) at the ends of
the scale, pulsing for intermediate values.

The units offer optional accessoires for
panel mounting, fuses and fuseholders,
current transformer, isolation
transformers

Main features

• Command input from analogue voltage

or current signal or potentiometer.

• Switching at voltage zero crossing.

• Partialization of wave train power with

dynamically optimized time cycle.

• Antiparallel double SCR

• 2 led for supply indication, “ON” state,

1 optional LED for load interrupt alarm

• 4000V isolation between input circuit
and power output

• MOV (varistor)

• Optional monitoring of interrupted load

• DIN rail mounting (standard);

Panel mounting (optional)

TECHNICAL DATA

General features

Category of use AC1
Nominal voltage

- 480Vac (max. range 24...530Vac)
Nominal frequency: 50/60Hz
Non-repetitive voltage: 1200Vp
Zero switching voltage: ≤ 20V
Voltage drop at nominal current ≤
1,4Vrms
Power factor = 1

Control inputs

Voltage: 0...5Vdc, 0...10Vdc

(impedance ≥100KΩ)

Current: 0...20mA, 4...20mA

(impedance 125Ω)
Potentiometer: from 1K to 10KΩ

(auto-fed by GTT)

Outputs

GTT 25 (SCR version)

Nominal current:
25A@40°C in continuous service
Non-repetitive overcurrent t=20 ms: 400A
I2t for blowout ≤ 645A2s
dV/dt critical with output deactivated:
1000V/µs

GTT 40 (SCR version)

Nominal current:
40A@40°C in continuous service
Non-repetitive overcurrent t=20 ms:
600A
I2t for blowout: ≤ 1010A2s
dV/dt critical with output deactivated:
1000V/µs

GTT 50 (SCR version)

Nominal current:
50A@40°C in continuous service
Non-repetitive overcurrent t=20 ms:
1150A
I2t for blowout: ≤ 6600A2s
dV/dt critical with output deactivated:
1000V/µs

GTT 60 (SCR version)

Nominal current:
60A@40°C in continuous service
Non-repetitive overcurrent t=20 ms:
1150A
I2t for blowout: ≤ 6600A2s
dV/dt critical with output deactivated:
1000V/µs

GTT 75 (SCR version)

Nominal current:
75A@40°C in continuous service
Non-repetitive overcurrent t=20 ms:
1300A
I2t for blowout: ≤ 8000A2s
dV/dt critical with output deactivated:
1000V/µs

GTT 90 (SCR version)

Nominal current:
90A@40°C in continuous service
Non-repetitive overcurrent t=20 ms:
1500A
I2t for blowout: ≤ 11200A2s
dV/dt critical with output deactivated:
1000V/µs

GTT 120 (versione SCR)

Nominal current:
120A@40°C in continuous service
(complete with fan and standard
thermostat).
Non-repetitive overcurrent t=20 ms:
1500A
I2t for blowout: ≤ 11200A2s
dV/dt critical with output deactivated:
1000V/µs

Isolation

Rated isolation voltage input/output:
4000Vac

Ambient conditions

• Working temperature:
0 to 80°C (see the dissipation
curves)

• Max. relative humidity:
50%...40°C

• Max. installation altitude:
2000m asl

• Pollution level: 2

• Storage temperature:

-20..+85°C

Power supply:

24Vac ±10%, 50/60 Hz
Absorptioni: 1.5VA
Max. isolation voltage: 300Vdc

Options:

Interrupted HB load alarm.
Controls the load by measuring
current on a shunt inside the device.
The alarm limit is set with a multirev
monorev trimmer.
The alarm output is obtained by
means of a solid state relay. The
contact is normally open (max. 30V,
150mA, conduction resistance 15
Ohm).

Installation notes

Use the high-speed fuse specified
in the catalog according to the
connection example given.

- Applications with solid state power
units must also include an automatic
safety switch to cut out the load
power line.
In order to obtain best reliability,
it is important to install a heatsink
correctly inside the panel, to reach
an adequate thermal exchange
between the device and the
surrounding air in natural convection
conditions.
Mount it vertically (max. 10°
dinclination from the vertical axis)

• Vertical distance between a device
and the panel walls >100mm

• Horizontal distance between a
device and the panel walls: at least
20mm

• Vertical distance between devices:
at least 300mm.

• Horizontal distance between
devices: at least 20 mm. Make sure
that the wire raceways do not reduce
such distances: if they do, install the
groups cantilevered to the panel so
that air can flow vertically over the
heat sink without obstructions.

Attention:
if you replace a GTT from an earlier
series, note the following:

- the GTT cannot be used as a slave
of a master GTT from a previous
series;

- the GTT can drive a slave from
a previous series only if a 10kW
resistance is connected in series to
the master/slave connection

- see the connection examples.

Limits of use

• Dissipation of thermic power on the
device with restraints on the ambient
temperature of the installation.

• Equip the cabinet with an external
air change or air-condition it, to put
out dissipated power.

• Installation restraints (distances to
be respected to grant dissipation with
natural convection).

• Line transistor max. voltage and
derivative limits, for which the
solid state relay is equipped with
inside safety devices (based on the
models).

• Leakage current < 3mA for SCR
version GTTs.
(max. value with rated voltage and
junction temperature of 125°C)

WORKING TYPOLOGY

“Zero crossing” with variable cycle time

Examples of the operation of the GTT for different values of the input drive signal and the consequent different cycle times
(100msec and 40msec respectively)

V

V

Example of input at 20% = 2V (IN 0-10V) or 4mA (IN 0-20mA)
V=Voltage across load

100msec

Logic output control for GTT

Example of input at 50% = 5V (IN 0-10V) or 10mA (IN 0-20mA)
V=Voltage across load

GTT thermal protection

40msec

Control
input

ON

OFF

t

Red LED ONRed LED

Thermal alarm

t

V = Load voltage

t

Thermal protection
activation

FACEPLATE DESCRIPTION

g

c

b

f

e

d

a

Synchronism signal for
Master/Slave connection

Alarm output

(solid state relay, HB option)

Green LED (power on),

Red LED (GTT running)

Red LED (thermal alarm), yellow LED

(load interrupt alarm, HB option)

NOT use

Monorev trimmer for minimum

calibration of input signal

Monorev trimmer for calibration of load

interrupt (HB) alarm limit

LINE connection

- control signal

+ control signal

Reference voltage for potentiometer power supply (+ 10V)

24 V ac 50/60 Hz power terminal

Dip switch for selection of input signal
(S1, S2, S3)

Monorev trimmer for maximum
calibration of load signal

LOAD connection

Reference connection of 230V line voltage

(HB option with 150V to 300V load)

Reference connection of 480V line voltage (HB option
with 300V to 530V load)

CALIBRATION PROCEDURE OF THE INPUT SIGNAL

The solid-state power unit, GTT, is supplied factory calibrated for 0..5V, 0..10V, 0..20mA, 4..20mA inputs, 10Kohm

potentiometer. Minimum and maximum values are adjusted with two monorev trimmers (d,e).
Input signal type is selected with the f adjustment dip switches (S1,S2,S3).

Control signal Dip Switch Position

e

S1 S2 S3

0...5Vdc OFF OFF ON

0...10Vdc ON OFF ON

0...20mA OFF ON ON

4...20mA OFF ON OFF

d

96%

82%

18%

4%

V/mA
In

V/mA
In

0-5V

0-10V

0-20mA

4-20mA

T

f

S1-S3

On

Off

Rin

100K�

100K�

125�

125�

Minimum adjustment trimmer (d) turned fully counterclockwise sets the start conducting limit at 4% of the signal; turned

fully clockwise, the minimum conducting limit is set at 18% of the input signal.

Maximum adjustment trimmer (e) turned fully clockwise sets the full conducting limit at 96% of the signal; turned fully

counterclockwise, the full conducting limit is set at 82% of the input signal<