Best place to locate a power factor correction capacitor

Yes! Distributing capacitors close to each motor will reduce the wiring resistance that handles both reactive and real currents. Thus less power loss will happen from just heating wires.

Also the parasitic values of real capacitors (ESR and ESL) will come into play. Capacitors distributed to one for each motor will typically result in a net lower Equivalent Series Resistance (ESR) than having one larger capacitor attached to the whole machine.

Since this is an already existing machine, space for these capacitors may not be available at each motor.

There might be some corrective action needed according to distance of capacitor bank from motors...

..."Q: The manual for the my motor says to keep the capacitor at least 10 cm from the motor. Is there a maximum distance?

A: No, there is not a published maximum distance. However, anything within 1 m or so should be fine. Much farther than that, and we get away from the designed 90 degree electrical phase shift that the capacitor was sized for, since the wire itself has inductance and capacitance. As a result, the motor runs less efficiently, and therefore hotter.
Long wire runs also results in voltage drops. That would mean that the capacitor phase would have less torque (proportional to the square, or up to 2.5 power, of the voltage drop)"...

So I would try to keep the capacitors close to the motors , and use a power analyzer when testing system, check power factors under expected operating conditions for each motor...

https://www.power-electronics.co.nz/blog/power-factor-correction-understanding-the-issues/

...."The general expression for power factor is given by

{\displaystyle {\mbox{power factor}}=P/P_{a}}
{\displaystyle P_{a}=I_{rms}V_{rms}}

where {\displaystyle P} is the real power measured by an ideal wattmeter, {\displaystyle I_{rms}} is the rms current measured by an ideal ammeter, and {\displaystyle V_{rms}} is the rms voltage measured by an ideal voltmeter. Apparent power, {\displaystyle P_{a}}, is the product of the rms current and the rms voltage.

If the load is sourcing power back toward the generator, then {\displaystyle P} and {\displaystyle {\mbox{power factor}}} will be negative."...

https://en.wikipedia.org/wiki/Power_factor

A potential problem I see with the large common capacitor for all of the motors is if the main contactor is switched on and off and on again before the bleeder resistor on the capacitor has discharged the capacitor fully. A sudden interruption of the power like a glitch,could possible do the same thing without an anti-short cycle timer.

This could result in a large amount of current to the capacitor,possibly overloading the wiring to the capacitor or damage to the capacitor.

This is another reason for locating the capacitors at the motor.

Having been involved not with motors but with a very large bank of triple fluro lights way back in an office block. Firstly the engineer in charge of design thought he would use non power factor corrected lights in the setup of over 300 lights.

However the current drawn from the circuit caused the multiphase breaker to trip. His remedy was to put in a bank of capacitors in an enclosure at the main switchboard however the circulating currents caused the cable to overheat and in the end we had to install 3 capacitors in each light, cheapness was costly in the end.

It is better to install the capacitors right at the motor. Are you sure that the capacitors don't serve a main purpose as a capacitor start, capacitor run unit. Or do they even provide a split phase system to enable the motor to start like a ceiling fan.

Having a large capacitor may appear economical but what happens when it fails and it will with the inductive/capacitive currents causing excessive ripple voltage. A case in point I have an AC welder with power correction capacitors of the correct voltage, ripple, capacity and heat value but they failed. when one fails the others are detrimentally effected. As a case in point the capacitors, amputee type, cost an arm and leg, from a major brand name all failed in succession leading to the breaker tripping.

In your case if one capacitor on a motor fails you have only lost 1/24 of the correction where as if a large one fails or loses quality, as they do and who ever checks them after installation with a capacity meter, all your correction is compromised and the supply current will go up. Ah yes the engineering solution tempered by a bean counter.

As in the case of the lighting bank corrected, the draw was 0.2A uncorrected it went to 0.8A per tube.

I would go with the option of one large capacitor placed after the Power contactor just before 24 sets of cables are taken out to individual 1HP motors.

This will be economical from the procurement, installation as well as maintenance point of view.

With capacitor in circuit, the contactor will not see the reactive part of the motor current and thus may work at a little lower than its rating, working cooler and giving better life.

It is the practice to size the Power contactor for total current without the capacitor compensation (so that the facility can work even if capacitor develops problem in service and needs to be disconnected).

If the installation already exists and there is no penalty charge on the incoming tariff for low power factor, then the best place to put the <…power factor correction capacitor…> is on eBay.

1. If the motors must all start together, Why a solid state relay for each motor?
2. Regulations/Codes for 1 hp motors require an overload relay/contactor/local emergency stop in my experience, an integrated unit local to motor is often used. A local capacitor may ease the spares provision and avoid main contactor/cable rating raised by uncompensated current.
3. Single or 3 phase not stated, SSR suggests 1 phase. Voltage not given - supposing 230 volt 1 ph suggests 100 amps for main contactor & cables, no p.factor compensation may increase main cable/contactor size. Do you allow for disconnect of single P.f. bank [fault] and operate with higher current?
4. Capacitors required appear to be ~35 microfarad//motor. These may be easier to get and cost less all-together than cap. 24 times value.
5. You will have to design /make control & protection/housing for a common cap. bank. Motor maker may offer integral cap. option.
6. With 24 motors located unknown distance apart, you may subdivide circuits & p.f. caps?

67model

There is actually a slight sequential delay in the web operation,the exit end starts a few milliseconds before the rest and the rest start in sequence from the exit towards the entrance.This prevents backlash and maintains tension on the roll.

Each station or access point has an E Stop hard wired that bypasses all software.

The E stops have redundant contacts.

Tension,speed, and current sensors on each motor detect a slow or stopped or overloaded motor and stop the entire operation in the proper sequence to prevent backlash,which can still happen in a catastrophic situation such as a sudden bearing lock up,but acoustic monitoring of the bearings make this very unlikely.