Voltage drop across Solid state relay?

[Jraef]

With a known good 24 VDC power supply its working fine.
117 Volts on the line side 116 Volts on the load, 1 V drop across the relay. Rigged it up to a space heater set a 600 Watts and its right at 5.6 Amp with my meter.
So the issue is elsewhere in the machine.

From the on-line manual, this is a zero cross output device, so the output voltage can be proportional to the input signal if it is pulsed. When you gave it +24VDC at home, that was not pulsed so it was gated fully on. At the panel, the control signal might be getting pulsed (PWM) so that the output is lower.

 

[tortuga]

Great info.
These solid state things just kinda snuck up on me.
All of a sudden they are everywhere.
Thanks everyone for your replies!

 

[gar]

200716-2145 EDT

I have found one datasheet for the SSR-40 DA. Rather poor, but does provide some insight to the device.

This part apparently uses a Triac as the output switch. In turn that means the device turns off at close to a load current zero crossing. The external load determines whether that is a source voltage crossing or not.

Apparently, if a low impedance control voltage between 3 and 32 V DC is used to control the SSR, then turn on occurs at the next input supply voltage zero crossing after application of the input control signal. No maximum impedance of this source is provided.

This SSR apparently responds to a resistive signal across the control terminals to make the device a phase shift dimmer. In this mode alone I would not call the device an SSR.

If something else controls the input resistor, then we have combined the SSR function with a phase shift dimmer.function,

The datasheet provides no information on trigger phase angle with respect to input resistance.

.. .

 

[Todd0x1]

200716-2145 EDT

I have found one datasheet for the SSR-40 DA. Rather poor, but does provide some insight to the device.

This part apparently uses a Triac as the output switch. In turn that means the device turns off at close to a load current zero crossing. The external load determines whether that is a source voltage crossing or not.

Apparently, if a low impedance control voltage between 3 and 32 V DC is used to control the SSR, then turn on occurs at the next input supply voltage zero crossing after application of the input control signal. No maximum impedance of this source is provided.

This SSR apparently responds to a resistive signal across the control terminals to make the device a phase shift dimmer. In this mode alone I would not call the device an SSR.

If something else controls the input resistor, then we have combined the SSR function with a phase shift dimmer.function,

The datasheet provides no information on trigger phase angle with respect to input resistance.

.. .

The Fotek SSR-40 comes in a few versions
The SSR-40DA the OP has is a normal DC input zero crossing trigger AC output SSR.
SSR-40VA would be the variable resistor phase control model with AC output.

Guessing out loud:
I wonder if whatever is driving the SSR is expecting a non zero crossing SSR and giving it pwm or phase proportional control and that original SSR got replaced with the wrong type. Perhaps the lower average voltage output is the result of the Zero Crossing SSR being supplied with a PWM control signal that is causing the SSR to turn on and off randomly skipping cycles.

 

[gar]

200716-2417 EDT

Todd0x1:

I did not pickup on the fact that the datasheet was for several
different models rather than a single model. For the DA model it should be only an ON-OFF device.

.

 

[gar]

200718-2035 EDT

tortuga:

I do not have an SSR like yours, but I have many simple OAC5s. The OAC5 probably uses a Triac power switch and a simple driver.

I connected a 50 W incandescent bulb as the load with my 120 V line as the power source. Used an HP regulated power supply as the control signal source.

I got three output states as control voltage was varied. These were off, partial on (likely 1/2 cycle), and on. Output was off for input less than 1.1 V, partially on for 1,1 to 1.15 V, and fully on for above 1.15 V. This characteristic can be expected, and this threshold voltage can be expected to vary somewhat with temperature, and the particular unit tested.

. .